Extraembryonic Membranes and Placentation in the Mexican Snake Conopsis lineata.

Extraembryonic membranes provide protection, oxygen, water, and nutrients to developing embryos, and their study generates information on the origin of the terrestrial egg and the evolution of viviparity. In this research, the morphology of the extraembryonic membranes and the types of placentation in the viviparous snake Conopsis lineata are described through optical microscopy during early and late gestation. When embryos develop inside the uterus, they become surrounded by a thin eggshell membrane. In early gestation, during stages 16 and 18, the embryo is already surrounded by the amnion and the chorion, and in a small region by the chorioallantois, which is product of the contact between the chorion and the growing allantois. A trilaminar omphalopleure covers the yolk sac from the embryonic hemisphere to the level of the equator where the sinus terminalis is located, and from there a bilaminar omphalopleure extends into the abembryonic hemisphere. Thus, according to the relationship of these membranes with the uterine wall, the chorioplacenta, the choriovitelline placenta, and the chorioallantoic placenta are structured at the embryonic pole, while the omphaloplacenta is formed at the abembryonic pole. During late gestation (stages 35, 36, and 37), the uterus and allantois are highly vascularized. The allantois occupies most of the extraembryonic coelom and at the abembryonic pole, it contacts the omphaloplacenta and form the omphalallantoic placenta. This is the first description of all known placenta types in Squamata for a snake species member of the subfamily Colubrinae; where an eggshell membrane with 2.9 µm in width present throughout development is also evident. The structure of extraembryonic membranes in C. lineata is similar to that of other oviparous and viviparous squamate species. The above indicates not only homology, but also that the functional characteristics have been maintained throughout the evolution of the reproductive type.

Remodeling of Uterine Tissues During Gestation of Potamotrygon wallacei (Elasmobranchii), a Neotropical Freshwater Stingray Endemic to the Negro River, Central Amazonia.

Neotropical freshwater stingrays of the subfamily Potamotrygoninae exhibit aplacental viviparity with uterine trophonemata. In this reproductive mode, females nourish and provide oxygenation to the embryo via the mucosa of the uterine wall. The aim of this study was to describe and histologically quantify the tissue components of the gravid uterus in an Amazonian freshwater stingray. Adult females of Potamotrygon wallacei were studied in different reproductive periods: resting stage, pregnant, and postpartum. During reproductive rest, the left ovary has numerous follicles compared to the right side. Therefore, uterine fertility is usually higher on the left side. The presence of an embryo in the right uterus suggests that the right ovary is also functional, although this only occurs in larger females. In females at reproductive rest, the wall of the uterus is formed by a mucosal layer (without the trophonemata) that contributes 16.7% to the thickness, while the myometrium accounts for 83.3% of the thickness. The mass-specific volume of the mucosal layer, inner circular, and outer longitudinal smooth muscle sheets tend to increase in the gravid uterus, indicating hypertrophy and hyperplasia of these components. During pregnancy, the trophonemata undergo marked tissue remodeling. Epithelial cells are organized into glandular acini and have apical secretory vesicles; furthermore, peripheral blood vessels proliferate and become dilated. These characteristics demonstrate that the gravid uterus of P. wallacei presents intense uterolactation activity and provides oxygenation to the fetus. Tissue remodeling occurs only in the uterus with the presence of an embryo. During postpartum, females have low body condition factor indicating a high reproductive cost. This study contributes to the knowledge of the reproductive biology of this species and will help us understand the impacts of climate change on the breeding areas of potamotrygonids.

Metabolic organization of pregnant freshwater stingray and their offspring.

The elucidation of energetic patterns in adult viviparous elasmobranchs and their offspring can contribute to understanding ecophysiological questions, such as maternal-fetal metabolism and group life-history traits. We characterized the energetic substrates in pregnant individuals and stages of offspring development in the freshwater stingray Potamotrygon amandae. Our results show that the energetic distribution of the yolk is composed of more lipids than proteins, whereas the inverse pattern is observed in the egg and uterus, proving the plasticity of the energy provision of the species. As a novelty, we describe that yolk/intestine transfer occurs in this species.

Placentation in the Mexican scincid lizard Plestiodon brevirostris (Squamata: Scincidae).

Viviparity is the reproductive pattern in which females gestate eggs within their reproductive tract to complete their development and give birth to live offspring. Within extant sauropsids, only the Squamata (e.g., snakes, lizards, and amphisbaenians) evolved viviparity, representing 20% of the existing species. The genus Plestiodon is represented by 43 species and is one of the most widely distributed genera of the Scincidae in Mexico. The goal of this research has been to determine the placental morphology and ontogeny during gestation in the lizard Plestiodon brevirostris. Specimens were dissected to obtain the embryonic chambers and the embryos were categorized to carry out the correlation between the development stage and the placenta development. The embryonic chambers were processed using the conventional histological technique for light microscopy. The identified embryonic stages were 4, 29, 34, 36, and 39. A thin eggshell surrounds the egg in early developmental stages; however, this structure is already absent in the embryonic hemisphere during the developmental stage 29. The results revealed that P. brevirostris is a lecithotrophic species, but a close maternal-fetal relationship is established by tissue apposition. Ontogenically, the placental types that form in the embryonic hemisphere are the chorioplacenta, choriovitelline placenta, and chorioallantoic placenta; whereas the omphaloplacenta is formed in the abembryonic hemisphere. The structure of the chorioallantoic placenta in P. brevirostris suggests that it may play a role during gas exchange between the mother and the embryo, due to the characteristics of the epithelia that comprise it. The structure of embryonic and maternal epithelia of the omphaloplacenta suggests a role in the absorption of the eggshell during gestation and possibly in the transport or diffusion of some nutrients. In general, it is evident that ontogeny and placental characteristics of P. brevirostris match those of other species of viviparous lecithotrophic scincids.

Live birth in a 47-million-year-old snake.

Viviparity is a widespread reproductive trait in snakes, although fossil evidence bearing on its evolution is extremely sparse. Here, we report an exceptional specimen of the minute booid snake Messelophis variatus recovered in the paleolake of the Messel Formation (early-middle Eocene, Germany). This gravid female contains at least two embryos located in the posterior third of the trunk region. The morphology, size, and degree of ossification of the cranial and postcranial remains indicate they correspond with late embryos. This specimen documents the first occurrence of viviparity in a fossil snake and extends the temporal distribution of this reproductive strategy in booid snakes by over 47 Ma. The evolution of viviparity in squamates has traditionally been associated with cold climates, but its presence at the dawn of the evolution of booids during early Palaeogene thermal peaks indicates that viviparity may have evolved under different selective pressures in this clade.

Increased superfetation precedes the evolution of advanced degrees of placentotrophy in viviparous fishes of the family Poeciliidae.

The causes and consequences of the evolution of placentotrophy (post-fertilization nutrition of developing embryos of viviparous organisms by means of a maternal placenta) in non-mammalian vertebrates are still not fully understood. In particular, in the fish family Poeciliidae there is an evolutionary link between placentotrophy and superfetation (ability of females to simultaneously bear embryos at distinct developmental stages), with no conclusive evidence for which of these two traits facilitates the evolution of more advanced degrees of the other. Using a robust phylogenetic comparative method based on Ornstein-Uhlenbeck models of adaptive evolution and data from 36 poeciliid species, we detected a clear causality pattern. The evolution of extensive placentotrophy has been facilitated by the preceding evolution of more simultaneous broods. Therefore, placentas became increasingly complex as an adaptive response to evolutionary increases in the degree of superfetation. This finding represents a substantial contribution to our knowledge of the factors that have shaped placental evolution in poeciliid fishes.

Unraveling Metabolite Provisioning to Offspring Through Parental Fluids: A Case Study of the Brazilian Guitarfish, Pseudobatos horkelii.

Elasmobranchs have a very distinct metabolism, and many aspects related to the energetic dynamics of these animals remain poorly investigated. The reproductive period is particularly vulnerable for viviparous species, as part of the energy reserves of the parental biomass is reallocated for gamete production and embryo development. In this context, this study aimed to characterize parental metabolite provisioning to the offspring (both sperm and developing embryos) of the Brazilian Guitarfish, Pseudobatos horkelii, through glucose, ß-hydroxybutyrate, triglycerides, and total cholesterol determinations in the uterine liquid (UL) and serum of pregnant females and in the seminal fluid (SF) and serum of males during the copulation period. No significant difference was observed for the analyzed markers between the UL and SF. Except for triglycerides, higher in female serum samples, all other energy markers were present at similar concentrations in the serum of both females and males. When comparing female UL and serum, significant differences were observed for triglycerides and total cholesterol. No differences were observed between SF and serum in males. The results indicate that all markers are being made available to offspring, possibly complementary to the yolk in the case of maternal liquid, and as an additional source for sperm mobilization required during egg fertilization in the case of the paternal fluid. Correlations between the markers in the parental matrices were also noted, compatible with the metabolic pathways activated during energy mobilization in vertebrates. Moreover, distinct marker predominance patterns were also noted for both UL and SF. Energy mobilization characterization directed to offspring through parental fluids aids in unraveling metabolic dynamics during the reproduction stage while also providing support for stress physiology studies to evaluate the indirect effects of parental allostatic overload in both sperm and developing embryos. Finally, energy mobilization assessments of parental fluids may also help elucidate how internal fertilization and viviparity evolved in this very distinct taxonomic group.

Effects of pregnancy on the body temperature of the South American rattlesnake, Crotalus durissus, in Southeastern Brazil

Changes in the body temperature (Tb) of reproductive females are well documented in squamate reptiles. However, the direction of these changes varies among species. Pregnant females may exhibit a lower or higher (and less variable) Tb than nonpregnant females. In some species, pregnancy has no detectable effect on female Tb. In this study, we compared the Tb of female rattlesnakes (Crotalus durissus) in different reproductive statuses (pregnant and nonpregnant) to investigate whether pregnancy influences Tb. We measured the Tb of female rattlesnakes kept in a semi-natural outdoor enclosure during summer and spring 2016 and summer 2017. Pregnant females selected a higher mean Tb than nonpregnant females. Moreover, we found significant differences in Tb among seasons. Body temperatures in summer 2017 were higher than in other seasons; however, reproductive status did not influence Tb variance. Therefore, our results agree with the hypothesis that females change their thermoregulatory behavior during pregnancy. Female rattlesnakes may increase their Tb during pregnancy to increase offspring fitness or to maximize their lifetime fitness.

Morphological basis for maternal nutrient provision to embryos in the viviparous fish Ataeniobius toweri (Teleostei: Goodeidae).

In viviparous Mexican fishes of the family Goodeidae, embryos develop in the maternal ovarian lumen. They typically absorb maternal nutrients during gestation by means of "trophotaeniae," that is, specialized, elongated extensions of the hindgut that are exposed to the fluids, which occupy the ovarian lumen. The sole exception is Ataeniobius toweri, whose embryos lack trophotaeniae but are nevertheless matrotrophic. Thus, how its embryos obtain maternal nutrients is unclear. We studied a series of non-pregnant and pregnant ovaries of A. toweri using histology to identify the mechanism of maternal-embryo nutrient transfer. By early-gestation, embryos have depleted their yolk supplies. Yolks are released into the ovarian lumen and are ingested by the developing embryos, as shown by yolk material in their digestive tracts. The embryonic gut is lined by an epithelium consisting of columnar cells with apical microvilli, providing a means for nutrient absorption. Contrary to statements in the literature, embryos develop minuscule trophotaenial rudiments that extend slightly into the ovarian lumen. These structures are formed of an absorptive epithelium that overlies a vascular stroma, similar to the trophotaeniae of other goodeids. Through late gestation, vitellogenic follicles form and oocytes are discharged into the ovarian lumen, contributing to embryonic nutrition. Thus, histological evidence suggests that embryos chiefly obtain nutrients from ingestion of yolk and maternal secretions released into the ovarian lumen. This function possibly is supplemented by uptake via the small hindgut protrusions and other absorptive surfaces (e.g., the skin and the gill epithelium). Our observations are consistent with two evolutionary interpretations of the hindgut protrusions: (a) that they are rudimentary, evolutionary precursors of trophotaeniae formed by exteriorized hindgut; and (b) that they are vestigial remnants of trophotaeniae that were lost during a switch to a form of matrotrophy involving nutrient ingestion.

Looking at the past to infer into the future: Thermal traits track environmental change in Liolaemidae.

The diversity of habitats generated by the Andes uplift resulted a mosaic of heterogeneous environments in South America for species to evolve a variety of ecological and physiological specializations. Species in the lizard family Liolaemidae occupy a myriad of habitats in the Andes. Here, we analyze the tempo and mode of evolution in the thermal biology of liolaemids. We assessed whether there is evidence of local adaptation (lability) or conservatism (stasis) in thermal traits. We tested the hypothesis that abiotic factors (e.g., geography, climate) rather than intrinsic factors (egg-laying [oviparous] or live-bearing [viviparous], substrate affinity) explain variation in field active body temperature (Tb ), preferred temperature (Tp ), hours of restriction of activity, and potential hours of activity. Although most traits exhibited high phylogenetic signal, we found variation in thermal biology was shaped by geography, climate, and ecological diversity. Ancestral character reconstruction showed shifts in Tb tracked environmental change in the past ∼20,000 years. Thermal preference is 3°C higher than Tb , yet exhibited a lower rate of evolution than Tb and air temperature. Viviparous Liolaemus have lower Tb s than oviparous species, whereas Tp is high for both modes of reproduction, a key difference that results in a thermal buffer for viviparous species to cope with global warming. The rapid increase in environmental temperatures expected in the next 50-80 years in combination with anthropogenic loss of habitats are projected to cause extirpations and extinctions in oviparous species.

Parallel evolution of placental calcium transfer in the lizard Mabuya and eutherian mammals.

An exceptional case of parallel evolution between lizards and eutherian mammals occurs in the evolution of viviparity. In the lizard genus Mabuya, viviparity provided the environment for the evolution of yolk-reduced eggs and obligate placentotrophy. One major event that favored the evolution of placentation was the reduction of the eggshell. As with all oviparous reptiles, lizard embryos obtain calcium from both the eggshell and egg yolk. Therefore, the loss of the eggshell likely imposes a constraint for the conservation of the egg yolk, which can only be obviated by the evolution of alternative mechanisms for the transport of calcium directly from the mother. The molecular and cellular mechanisms employed to solve these constraints, in a lizard with only a rudimentary eggshell such as Mabuya, are poorly understood. Here, we used RT-qPCR on placental and uterine samples during different stages of gestation in Mabuya, and demonstrate that transcripts of the calcium transporters trpv6, cabp28k, cabp9k and pmca are expressed and gradually increase in abundance through pregnancy stages, reaching their maximum expression when bone mineralization occurs. Furthermore, CABP28K/9K proteins were studied by immunofluorescence, demonstrating expression in specific regions of the mature placenta. Our results indicate that the machinery for calcium transportation in the Mabuya placenta was co-opted from other tissues elsewhere in the vertebrate bodyplan. Thus, the calcium transportation machinery in the placenta of Mabuya evolved in parallel with the mammalian placenta by redeploying the expression of similar calcium transporter genes.

Plasma energetic substrates and hepatic enzymes in the four-eyed fish Anableps anableps (Teleostei: Cyprinodontiformes) during the dry and rainy seasons in the Amazonian Island of Maracá, extreme north of Brazil

ABSTRACT Anableps anableps is a viviparous teleost typical from Amazon Delta estuaries. It is representative of this biome in Maracá, which offers a potential for biomonitoring. The aim of this study is to apply different biomarkers to males and females of this species and verify possible seasonal influences on their physiology. To collect fish, three expeditions were carried out from the rainy season of April 2018 to the rainy season of February 2019. Biometric parameters and gonadosomatic (GSI), hepatosomatic (HSI), and viscerosomatic (VSI) indexes were calculated, and blood samples were taken to measure triglycerides, total proteins, glucose, and activity of the enzymes aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP). The GSI of males is higher in the rainy season and of females in the dry season. This is probably related to the embryogenesis process. Males show an increase in biomass during the dry season, a metabolic homogeneity, and females show an increase in plasma glucose, triglycerides, and ALT activity. The tested biomarkers are potential for biomonitoring, preliminarily suggesting that there is a seasonal asynchronism between males and females of A. anableps as for the allocation of energy resources at different times of their life cycle.

RESUMO Anableps anableps é um teleósteo vivíparo típico de estuários do Delta do Rio Amazonas, sendo representativo deste bioma na ilha de Maracá, com potencial para o biomonitoramento. O objetivo deste estudo foi aplicar diferentes biomarcadores em machos e fêmeas desta espécie e verificar a possível influência sazonal em aspectos de sua fisiologia. Para a coleta dos peixes foram realizadas três expedições, de abril/2018 (estação chuvosa), setembro/2018 (estação seca) até fevereiro/2019 (estação chuvosa). Foram obtidos parâmetros biométricos, índices gonadossomático (IGS), hepatossomático (IHS), viscerossomático (IVS) e amostras de sangue para dosagem de triglicerídeos, proteínas totais, glicose e a atividade das enzimas aspartato aminotransferase (AST), alanina aminotransferase (ALT) e fosfatase alcalina (ALP). O IGS dos machos foi maior na estação chuvosa e das fêmeas na estação seca, isso provavelmente ocorreu devido ao processo de embriogênese. Os machos aumentaram a biomassa na estação seca e apresentaram homogeneidade metabólica, já as fêmeas apresentaram hiperglicemia, hipertrigliceridemia e maior atividade da ALT. Os biomarcadores testados mostraram-se promissores para o biomonitoramento, sugerindo de forma preliminar que há um assincronismo sazonal entre machos e fêmeas de A. anableps na alocação de recursos energéticos em diferentes momentos do seu ciclo de vida.

Plasma estradiol and progesterone concentrations during the female reproductive cycle in a highly placentotrophic viviparous lizard, Mabuya sp.

The neotropical genus Mabuya are obligate placentotrophic viviparous lizards, which have a short vitellogenesis that produces microlecithal oocytes and a prolonged time of gestation (9 to 10 months). The hormonal control of female reproductive activity during follicular growth and pregnancy has not been studied, although it is known that the corpus luteum can produce progesterone, but regresses early in pregnancy, being replaced in this function by the placenta. Through enzyme immunoassay (EIA) we measured the plasma concentrations of estradiol (E2) and progesterone (P4) in females of a population of Mabuya sp at different stages of their reproductive cycle. Previously, we confirmed the presence of P4 in plasma by high-performance liquid chromatography methods with diode-array detector ultraviolet (HPLC-DAD-UV). The average concentration values of E2 and P4 were compared among reproductive stages and their dynamics were related to what is known in other oviparous and viviparous amniotes. The plasma E2 concentrations of Mabuya sp. are below the levels found in other viviparous reptiles, probably related to the substantial reduction of its follicular growth phase. Its highest concentration was detected during vitellogenesis, related to its function in the growth and maturation of the ovarian follicles and oviduct preparation for pregnancy; lower levels were observed during pregnancy, but they increase at the end when a new vitellogenesis event begins and massive placental maternal-fetal nutrient transfer occurs. High concentrations of P4 were found during pregnancy, related to its function in the maintenance of the developing embryos within the oviduct. The highest levels of P4 were found at early gestation, then they descend from mid-gestation to the end of gestation. Although some characteristics of hormonal control related to the high level of placentotrophy were observed in this species, the changes in plasma sex steroid concentrations during the reproductive cycle in females of Mabuya sp. follow patterns seen in other viviparous amniotes.

Effects of biological traits on capture-induced parturition in a freshwater stingray and perspectives for species management.

Elasmobranchs are particularly vulnerable to overexploitation and population depletion, especially due to their life-history traits, such as low reproductive output and slow growth. Given that capture-induced parturition (abortion or premature birth) is a common consequence of fisheries in elasmobranchs, but still little studied, we investigated how the abortion/premature birth process varies in response to reproductive traits in a freshwater stingray, Potamotrygon amandae. Our results revealed that capture-induced parturition was affected by reproductive traits, such as litter size (one to seven) and gestation stage. The event occurred faster in pregnant females with high litter size during late pregnancy. Also, as found in other elasmobranchs, litter size was positively correlated with maternal size. These findings indicate that larger pregnant females in late pregnancy are more vulnerable to capture-induced parturition. This study improves our understanding of the capture-induced parturition process in stingrays, and provides useful information for management strategies and future recommendations for elasmobranch conservation.

Predation risk shapes the degree of placentation in natural populations of live-bearing fish.

The placenta is a complex life-history trait that is ubiquitous across the tree of life. Theory proposes that the placenta evolves in response to high performance-demanding conditions by shifting maternal investment from pre- to post-fertilisation, thereby reducing a female's reproductive burden during pregnancy. We test this hypothesis by studying populations of the fish species Poeciliopsis retropinna in Costa Rica. We found substantial variation in the degree of placentation among natural populations associated with predation risk: females from high predation populations had significantly higher degrees of placentation compared to low predation females, while number, size and quality of offspring at birth remained unaffected. Moreover, a higher degree of placentation correlated with a lower reproductive burden and hence likely an improved swimming performance during pregnancy. Our study advances an adaptive explanation for why the placenta evolves by arguing that an increased degree of placentation offers a selective advantage in high predation environments.

Estrutura da placenta epiteliocorial em tubarões e sua interação materno-fetal / Epitheliochorial placental structure in sharks and its materno-fetal interaction

Em mamíferos, a nutrição intrauterina de embriões ocorre através da placenta. Porém, em tubarões vivíparos placentários da ordem Carcharhiniformes (famílias Leptochariidae, Triakidae, Hemigaleidae e Carcharhinidae), a nutrição de embriões pode ocorrer de três formas: lecitotrofia (vitelo); histotrofia (secreções uterinas) e placentotrofia. Nesta revisão, é discutida a similitude anatômica, fisiológica e, principalmente imunológica, entre as placentas de tubarões e de mamíferos, mostrando que a tolerância materno-fetal em tubarões placentários e mamíferos é dependente de proteínas como a indoleamina 2,3 – dioxigenase, interleucina-1 e proteínas específicas da gestação.

In mammals, intrauterine nutrition of embryos occurs through the placenta. However, in placental viviparous sharks of the order Carcharhiniformes (families Leptochariidae, Triakidae, Hemigaleidae and Carcharhinidae), embryo nutrition can occur in three ways: lecitotrophy (yolk); histotrophy (uterine secretions) and placentotrophy. In this review, it is discussed the anatomical, physiological, and mainly immunological similarity between the placenta of sharks and mammals, showing that maternal-fetal tolerance in placental and mammalian sharks is dependent on proteins such as indoleamine 2,3-dioxygenase, interleukin- 1 and specific proteins of gestation.

Estrutura da placenta epiteliocorial em tubarões e sua interação materno-fetal / Epitheliochorial placental structure in sharks and its materno-fetal interaction

Em mamíferos, a nutrição intrauterina de embriões ocorre através da placenta. Porém, em tubarões vivíparos placentários da ordem Carcharhiniformes (famílias Leptochariidae, Triakidae, Hemigaleidae e Carcharhinidae), a nutrição de embriões pode ocorrer de três formas: lecitotrofia (vitelo); histotrofia (secreções uterinas) e placentotrofia. Nesta revisão, é discutida a similitude anatômica, fisiológica e, principalmente imunológica, entre as placentas de tubarões e de mamíferos, mostrando que a tolerância materno-fetal em tubarões placentários e mamíferos é dependente de proteínas como a indoleamina 2,3 dioxigenase, interleucina-1 e proteínas específicas da gestação.(AU)

In mammals, intrauterine nutrition of embryos occurs through the placenta. However, in placental viviparous sharks of the order Carcharhiniformes (families Leptochariidae, Triakidae, Hemigaleidae and Carcharhinidae), embryo nutrition can occur in three ways: lecitotrophy (yolk); histotrophy (uterine secretions) and placentotrophy. In this review, it is discussed the anatomical, physiological, and mainly immunological similarity between the placenta of sharks and mammals, showing that maternal-fetal tolerance in placental and mammalian sharks is dependent on proteins such as indoleamine 2,3-dioxygenase, interleukin- 1 and specific proteins of gestation.(AU)

Novel placental structure in the Mexican gerrhonotine lizard, Mesaspis viridiflava (Lacertilia; Anguidae).

The evolution of viviparity alters the physical relationship between mothers and offspring and the prevalence of viviparity among squamate reptiles presents an opportunity to uncover patterns in the evolution of placental structure. Understanding the breadth of this diversity is limited because studies of placental structure and function have emphasized a limited number of lineages. We studied placental ontogeny using light microscopy for an embryological series of the Mexican gerrhonotine lizard, Mesaspis viridiflava. This species develops an elaborate yolk sac placenta, an omphaloplacenta, which receives vascular support arising in a structure known only from other gerrhonotine lizards. A prominent feature of the omphaloplacenta is a zone of uterine and embryonic epithelial cell hyperplasia located at the upper shoulder of the yolk mass, often extending above the yolk mass. The omphaloplacenta covers more than one-half of the surface area of maternal-embryonic contact. The chorioallantoic placenta has a more restricted distribution because the allantois remains in the embryonic hemisphere of the egg throughout development and lies internal to the vascular support for the omphaloplacenta in areas where they overlap. The structural profile of the chorioallantoic placenta indicates a potential for respiratory exchange and/or hemotrophic nutritive transport, while that of the omphaloplacenta suggests that nutritive transfer is primarily via histotrophy. An eggshell is present in the earliest embryonic stages examined but regresses relatively early in development. Placental specializations of this species are consistent with a pattern of matrotrophic embryonic nutrition and have evolved in a unique lineage specific developmental pattern.

How mountains shape biodiversity: The role of the Andes in biogeography, diversification, and reproductive biology in South America's most species-rich lizard radiation (Squamata: Liolaemidae).

Testing hypotheses on drivers of clade evolution and trait diversification provides insight into many aspects of evolutionary biology. Often, studies investigate only intrinsic biological properties of organisms as the causes of diversity, however, extrinsic properties of a clade's environment, particularly geological history, may also offer compelling explanations. The Andes are a young mountain chain known to have shaped many aspects of climate and diversity of South America. The Liolaemidae are a radiation of South American reptiles with over 300 species found across most biomes and with similar numbers of egg-laying and live-bearing species. Using the most complete dated phylogeny of the family, we tested the role of Andean uplift in biogeography, diversification patterns, and parity mode of the Liolaemidae. We find that the Andes promoted lineage diversification and acted as a species pump into surrounding biomes. We also find strong support for the role of Andean uplift in boosting the species diversity of these lizards via allopatric fragmentation. Finally, we find repeated shifts in parity mode associated with changing thermal niches, with live-bearing favored in cold climates and egg-laying favored in warm climates. Importantly, we find evidence for possible reversals to oviparity, an evolutionary transition believed to be extremely rare.

Chrysomelinae species (Coleoptera, Chrysomelidae) and new biological data from Rio de Janeiro, Brazil.

Chrysomelinae is one of the largest subfamilies in Chrysomelidae, yet much basic information remains unknown for Neotropical species. The present study aims to compile the first regional list of Chrysomelinae for the State of Rio de Janeiro, Brazil, and assemble natural history traits obtained from our fieldwork from 2005 to 2010 in Serra dos Órgãos National Park, a mountainous area of Atlantic forest. The species list was compiled from data from field work, collections, and literature, and recorded a total of 100 species, belonging to 21 genera in one tribe (Chrysomelini) and three subtribes: Chrysolinina (91 species), Chrysomelina (eight species) and Entomoscelina (one species). Of these, 91 species are new records for the state. Serra dos Órgaõs National Park holds records of 43 species, with Platyphora being the most species-rich genus, and Solanaceae the most common host plant family. Some new records of reproductive mode (larviparous vs. oviparous) and larval behavior are also given. These Brazil Chrysomelinae species exhibited a clear seasonal pattern, with more species recorded in the hot and rainy season from October to January, and considerably fewer species from June to August, during the drier and colder months. The fraction of new records in comparison with published species and natural history information illustrates how little we know of Chrysomelinae in the state and in the country.