Dan Warner (left) and Tim Mitchell (right) beside their poster on impacts of population density and time of hatching on survival and early life phenotypes of Anolis sagrei
Tim Mitchell a post-doctoral researcher at University of Minnesota with Emilie Snell-Rood presented his work from his prerious post doc in Dan Warner’s lab where he investigated the impacts of density and timing of hatching on the survival and growth of Anolis sagrei hatchings. Seeking to specifically address these questions:
How does investment in offspring size and number shift seasonally?
Does the timing of hatching influence survival or growth in the field?
And does adult density influence survival or growth of hatchlings in the field?
Adult anoles were brought into the lab on three different dates and breeding was split into three corresponding windows of time: Cohort 1 (February 23rd – April 27th), Cohort 2 (June 18th – July 30th), and Cohort 3 (September 5th – October 15th). On experimental islands, adult densities were manipulated to create high and low lizard densities. Hatchlings from cohorts 1, 2, and 3 were released onto high and low adult density islands in June, August, and October, respectively, and researchers returned the following spring to recapture the marked lizards.
Breeding in the lab revealed a seasonal shift from producing more smaller offspring early to producing fewer larger offspring later in the season. Adult densities on the islands did not affect hatchling survival, but there was a substantial survival advantage to being an early-hatched lizard. Size and growth of hatchlings were influenced both by timing of hatching and the adult densities. So happy to catch up with my academic family and see the cool research they are doing!
Effects of urbanization pose major challenges to biological systems globally. One example that impacts the thermal environments of urban areas is the urban heat island effect, where urbanization creates an environment that is hotter than nearby natural areas. In Shane Campbell-Staton’s talk “Temperature-mediated shifts in performance and gene expression between populations of the Puerto Rican crested anole in natural and urban habitats” he sought to investigate divergence in thermal physiology and gene expression between urban and natural populations of anoles in Puerto Rico.
In situ, he investigated whether there were differences in urban and natural microhabitats, lizard thermal tolerance between urban and natural populations, and if there were differences in thermal physiology if this was a plastic or genetic response. He found that urban microhabitats were warmer, and that lizards from urban environments maintained function at higher temperatures when compared to their natural environment counterparts. This increase in thermal tolerance is a plastic response in the urban lizards. He then investigated the transcriptomics to investigate if there is evidence for temperature-mediated selection in urban heat islands, and found that selection on ancestral plasticity may play a role in acclimation to urban heat stressors. Future work includes identify genes involved in this accommodation. Amazing things to come!