Wildlife trade shifts from brick-and-mortar markets to virtual marketplaces: A case study of birds of prey trade in Thailand.

The shift of wildlife trade from brick-and-mortar markets to virtual online marketplaces is reported using the trade of birds of prey (raptors) in Thailand from 1968 to 2019 as a case study. We analyzed data obtained from physical market survey data for 2,782 individuals from 27 species, with 2,420 individuals reported in early surveys (1968-1988) and 362 individuals reported in later surveys (2003-2015) and online surveys (February 2017 to January 2019). We compared information on asking prices and what species were traded using two comparative approaches to analyze how species composition may have changed over time (physical markets and online platforms; pre-Internet and Internet era). In comparison with the five previous market surveys, we did not find a statistically significant difference between species and availability of species offered for sale when comparing physical bird markets and online markets. In all data sets, biological factors such as wingspan were significant factors in explaining price variation. We conclude that sustained monitoring is needed to make direct comparisons between the trade platforms. With a continued increase of wildlife trade on online platforms, we recommend increased regulation and enforcement of wildlife trade laws.

The complexity of mating decisions in stalk-eyed flies.

All too often, studies of sexual selection focus exclusively on the responses in one sex, on single traits, typically those that are exaggerated and strongly sexually dimorphic. They ignore a range of less obvious traits and behavior, in both sexes, involved in the interactions leading to mate choice. To remedy this imbalance, we analyze a textbook example of sexual selection in the stalk-eyed fly (Diasemopsis meigenii). We studied several traits in a novel, insightful, and efficient experimental design, examining 2,400 male-female pairs in a "round-robin" array, where each female was tested against multiple males and vice versa. In D. meigenii, females exhibit strong mate preference for males with highly exaggerated eyespan, and so we deliberately constrained variation in male eyespan to reveal the importance of other traits. Males performing more precopulatory behavior were more likely to attempt to mate with females and be accepted by them. However, behavior was not a necessary part of courtship, as it was absent from over almost half the interactions. Males with larger reproductive organs (testes and accessory glands) did not make more mating attempts, but there was a strong tendency for females to accept mating attempts from such males. How females detect differences in male reproductive organ size remains unclear. In addition, females with larger eyespan, an indicator of size and fecundity, attracted more mating attempts from males, but this trait did not alter female acceptance. Genetic variation among males had a strong influence on male mating attempts and female acceptance, both via the traits we studied and other unmeasured attributes. These findings demonstrate the importance of assaying multiple traits in males and females, rather than focusing solely on prominent and exaggerated sexually dimorphic traits. The approach allows a more complete understanding of the complex mating decisions made by both males and females.

Is the scaling of swim speed in sharks driven by metabolism?

The movement rates of sharks are intrinsically linked to foraging ecology, predator-prey dynamics and wider ecosystem functioning in marine systems. During ram ventilation, however, shark movement rates are linked not only to ecological parameters, but also to physiology, as minimum speeds are required to provide sufficient water flow across the gills to maintain metabolism. We develop a geometric model predicting a positive scaling relationship between swim speeds in relation to body size and ultimately shark metabolism, taking into account estimates for the scaling of gill dimensions. Empirical data from 64 studies (26 species) were compiled to test our model while controlling for the influence of phylogenetic similarity between related species. Our model predictions were found to closely resemble the observed relationships from tracked sharks, providing a means to infer mobility in particularly intractable species.