Flower morphology as a predictor of pollination mode in a biotic to abiotic pollination continuum.

BACKGROUND AND AIMS: Wind pollination has evolved repeatedly in flowering plants, yet the identification of a wind pollination syndrome as a set of integrated floral traits can be elusive. Thalictrum (Ranunculaceae) comprises temperate perennial herbs that have transitioned repeatedly from insect to wind pollination while also exhibiting mixed pollination, providing an ideal system to test for evolutionary correlation between floral morphology and pollination mode in a biotic to abiotic continuum. Moreover, the lack of floral organ fusion across this genus allows testing for specialization to pollination vectors in the absence of this feature. METHODS: We expanded phylogenetic sampling in the genus from a previous study using six chloroplast loci, which allowed us to test whether species cluster into distinct pollination syndromes based on floral morphology. We then used multivariate analyses on floral traits followed by ancestral state reconstruction of the emerging flower morphotypes and determined whether these traits are evolutionarily correlated under a Bayesian framework with Brownian motion. KEY RESULTS: Floral traits fell into five distinct clusters, which were reduced to three after considering phylogenetic relatedness and were largely consistent with flower morphotypes and associated pollination vectors. Multivariate evolutionary analyses found a positive correlation between the lengths of floral reproductive structures (styles, stigmas, filaments and anthers). Shorter reproductive structures tracked insect-pollinated species and clades in the phylogeny, whereas longer structures tracked wind-pollinated ones, consistent with selective pressures exerted by biotic vs. abiotic pollination vectors, respectively. CONCLUSIONS: Although detectable suites of integrated floral traits across Thalictrum were correlated with wind or insect pollination at the extremes of the morphospace distribution, a presumed intermediate, mixed pollination mode morphospace was also detected. Thus, our data broadly support the existence of detectable flower morphotypes from convergent evolution underlying the evolution of pollination mode in Thalictrum, presumably via different paths from an ancestral mixed pollination state.

Claws and toepads in mainland and island Anolis (Squamata: Dactyloidae): Different adaptive radiations with intersectional morphospatial zones.

Anolis lizards have evolved morphologies in response to different selective factors related to microhabitat use. Morphological diversity exhibits evolutionary patterns that reveal similarities and unique regional traits among the mainland and island environments and among Greater Antilles and Lesser Antilles islands. In the Greater Antilles and mainland environments anole species are classified into morphological/ecological groups, that are known as morphotypes (mainland) or ecomorphs (Greater Antilles). Morphotypes are defined only with morphological information; in contrast, for ecomorph assignment both morphology and ethology are required. For mainland species distributed in northwestern South America 10 morphotypes were proposed to include the morphological diversity of 59 species. We obtained data from body size, limbs length, tail length, and the number of lamellae for an additional ten species occurring in the same region and assigned them into morphotypes. We also collected data of the claw and toepad diversity of mainland and island Anolis from northwestern South America and compared it to the claw and toepads morphology recorded for the Greater Antilles and Lesser Antilles islands, under a phylogenetic framework. We found new island morphotypes (MT11-MT13) of Anolis from northwestern South America. When comparing claws and toepads morphology among the 13 morphotypes we found that morphological variation of these traits partially corresponds to morphotype groups. For instance, habitat specialist species like Anolis heterodermus, classified in morphotype 4 (MT4), have a characteristic design of broad toepad and reduced claws, and non-unique design of toepads and claws occurs in morphotypes MT1, MT2, MT5, MT10, and MT13. We also compared claws and toepads of fore and hindlimbs within the same individual, and found that even if limbs show differences in claws and toepads, suggesting that they perform differential biomechanical function, the degree of within individual variation is specific and not related to morphotype assignment. Our data supported the convergent and unique regional evolution among mainland and island anoles, and revealed aspects of correlative evolution of functional traits of claws and toepads that probably are related to minor differences in microhabitat use among mainland and island species, as suggested by previously published literature. Lastly, the evolutionary pattern of morphological diversity of claws and toepads of Anolis in the mainland and island environment supports both unique regional traits and common selective and historical factors that have molded Anolis morphological diversity.

Adaptation and coordinated evolution of plant hydraulic traits.

Hydraulic properties control plant responses to climate and are likely to be under strong selective pressure, but their macro-evolutionary history remains poorly characterised. To fill this gap, we compiled a global dataset of hydraulic traits describing xylem conductivity (Ks ), xylem resistance to embolism (P50), sapwood allocation relative to leaf area (Hv) and drought exposure (ψmin ), and matched it with global seed plant phylogenies. Individually, these traits present medium to high levels of phylogenetic signal, partly related to environmental selective pressures shaping lineage evolution. Most of these traits evolved independently of each other, being co-selected by the same environmental pressures. However, the evolutionary correlations between P50 and ψmin and between Ks and Hv show signs of deeper evolutionary integration because of functional, developmental or genetic constraints, conforming to evolutionary modules. We do not detect evolutionary integration between conductivity and resistance to embolism, rejecting a hardwired trade-off for this pair of traits.