Data and R code for: Temperature-induced multispecies cohort effects in sympatric snakes

In reptiles, reproductive maturity is often determined by size rather than age. Consequently, growth early in life may influence population dynamics through effects on generation time and survival to reproduction. Because reproductive phenology and pre- and post-natal growth are temperature-dependent, environmental conditions may induce multi-species cohort effects on body size in sympatric reptiles. I present evidence of this using ten years of neonatal size data for three sympatric viviparous snakes, Dekay’s Brownsnakes (Storeria dekayi), Red-bellied Snakes (S. occipitomaculata) and Common Gartersnakes (Thamnophis sirtalis). End-of-season neonatal size varied in parallel across species such that snout-vent length was 36-61% greater and mass was 65-223% greater in years when gestating females could achieve higher April-May (vs. June-July or August-September) operative temperatures. Thus, temperature had a larger impact during follicular enlargement and ovulation than during gestation o..., ,

在爬行动物中，繁殖成熟度通常由体型而非年龄决定。因此，生命早期的生长可通过影响世代时间与繁殖存活率，进而作用于种群动态。由于繁殖物候（reproductive phenology）、产前及产后生长均受温度调控，环境条件可能对同域分布的爬行动物种群体型产生多物种种群同期群效应。本研究依托3种同域卵胎生（viviparous）蛇类——德凯棕蛇（Storeria dekayi）、红腹蛇（S. occipitomaculata）及普通束带蛇（Thamnophis sirtalis）的10年新生个体体型监测数据，为上述现象提供了实证支撑。各物种的季末新生个体体型均呈现同步变化：当妊娠雌体在4-5月可获得更高有效温度（operative temperatures）时，新生个体吻肛长（snout-vent length）较6-7月或8-9月的年份增加36%-61%，体重增加65%-223%。温度在滤泡发育与排卵阶段的影响大于妊娠阶段……