The microbiota, the set of microorganisms associated with a particular environment or host, has acquired a prominent role in the study of many physiological and developmental processes. Here I explore a possible role of the microbiota in regeneration, focusing primarily on the regeneration of the intestine in the sea cucumber Holothuria glaberrima, an echinoderm common in local waters. In CHAPTER 1, I review the involvement of the microbiota in regeneration-related cellular events, providing examples of regenerative models that extend from the repair of tissue layers to the regeneration of complete organs or animals. In addition, I highlight the role of the microbiota in the digestive tract, in echinoderms, primarily holothuroids, which are models for regeneration studies. As a first step in these studies, I characterize the microbiota of normal and regenerating animals (CHAPTER 2). In this chapter the microbial community of sea cucumbers undergoing intestinal regeneration was studied using 16S rRNA amplicon sequencing. For this, sea cucumbers were eviscerated and left to regenerate in seawater aquaria for up to 21 days. Among the findings reported are: (i) the existence of microbial compartmentalization in normal animals which changes in regenerating animals. (ii) a strong effect of the environment, in this case the closed aquarium system, on the normal and regenerating microbiota, (iii)) an increase in species richness and evenness in regenerating animals and (iv) differential abundance of specific bacterial taxa. To determine the role of the microbiota in the regeneration process an initial approach was executed in the following chapters. CHAPTER 3, shows the experiments where the effects of various antibiotics on intestinal regeneration of H. glaberrima were evaluated. For this, eviscerated holothurians were exposed to different antibiotic cocktails and left to regenerate for 10 days. Immunohistological and histochemical analyses were performed to analyze regenerative processes, including rudiment size, extracellular matrix (ECM) remodeling, cell proliferation, and muscle dedifferentiation. Reduction in muscle dedifferentiation, ECM remodeling, and the size of their regenerating rudiments were observed in antibiotic-treated animals in comparison to untreated ones. Our results demonstrate a negative effect of antibiotics on intestinal regeneration and strongly suggest that these effects are due to alterations in the microbial community. To discard the possibility that the antibiotics directly affect holothurian metabolic activity, their effect on the metabolism of H. glaberrima tissues was assayed. A second approach to test the effect of microbiota on intestinal regeneration is shown on CHAPTER 4. Here I utilized fecal microbial transplants (FMT) to validate the effectiveness of microbial transplants in enhancing intestinal regeneration. For this, eviscerated holothuroids, exposed to antibiotics prior to evisceration, were subjected to FMT from non-eviscerated donors. Control animals received no FMT or autoclaved FMT. Bacterial samples were cultured from each group to verify if antibiotics could induce changes in the animal microbiota. Histological analysis revealed that different combinations of antibiotics, along with FMT, have specific effects on various regeneration processes. These findings support the role of the microbiota in the sea cucumber's intestinal regeneration process, reveal factors contributing to organ regeneration, and provide insight into little studied functions of the gut microbiota....

Global climate is changing at unprecedented rates, causing detrimental effects on vulnerable organisms and forcing them to cope with unfavorable conditions. Ectotherms often adapt to changing abiotic variables by altering their distribution ranges. Amphibians are known to alter their distribution because of rising temperatures. In Puerto Rico we have observed a range-shift to higher elevations in one species of direct-developing frog. Here we considered two species that occur sympatrically in part of their range at El Yunque tropical montane reserve. One species, Eleutherodactylus portoricensis, is presently limited to high elevations above 700 m.a.s.l., although it was previously found down to 400 m.a.s.l. Contrastingly, its congeneric E. coqui, can be found at all elevations (0-1,300 m.a.s.l.). Our objective was to characterize both species’ thermo-physiological profiles and question if the observed range-shift to higher elevations of E. portoricensis was associated to higher physiological sensitivity. We evaluated critical thermal minima and maxima, and thermal preference for three populations: E. portoricensis (850m), and low (180m) and highland (850m) E. coqui. We also evaluated dehydration stress during jumping performance by reducing 5% of their body mass using dry-air chambers. Lastly, we modeled E. portoricensis current and future distribution range under various scenarios of climate change. Our results show that E. portoricensis has a narrower thermal tolerance range and prefers lower temperatures when given a gradient. Also, E. portoricensis showed lower performance levels than E. coqui when dehydrated. Our results suggest that higher physiological sensitivity may explain elevational range contraction on this species. In addition, distribution models show a decrease in occurrence probability later this century in comparison to current projections. Our models also predict a range contraction towards higher elevations. This range shift would most likely result in the extirpation of most E. portoricensis populations. This research highlights the vulnerability of an endemic tree frog in Puerto Rico as a consequence of anthropogenic climate change and the urge to develop effective conservation efforts....

Corals can exhibit much variability in life-history strategies. A proposed categorization recognizes competitive, stress-tolerant and weedy species. 'Competitive' corals invest more energy towards growth, 'stress-tolerant' towards maintenance and 'weedy' towards reproduction. While competitive corals are declining due to climate change and anthropogenic stressors, stress-tolerant and weedy are thriving. We performed a reciprocal transplant experiment between a degraded and a more pristine reef, and measured the physiological (Symbiodinium density, chlorophyll a concentration, protein concentration) and immunological (oxidative stress) response of the stresstolerant Pseudodiploria strigosa and Orbicella annularis, and the weedy Porites astreoides. Results indicate that the studied species can rapidly and successfully acclimate to local environmental conditions. Comparisons among species suggest that the physiological and immunological response in P. astreoides, P. strigosa and O. annularis are more influenced by species-specificity than by life-history strategy....

In this thesis, we explore the cognitive basis for the emergence of individual foraging strategies (IFS) across multiple honey bee subspecies using Reversal Learning assays and Free-Flying foraging problems. In Chapter 1 ...

Butterfly wing patterns have captivated evolutionary and developmental biologists for decades because of their vast diversity. Studies have focused on the molecular basis of pattern variation in the Nymphalidae, with little effort put toward skippers, family Hesperiidae. This study had two aims: identify the presence of Wnt genes through ISH and pharmacological drug injections, and test differentially expressed genes in three developmental stages, between wing types, and between wing compartments of E. clarus using RNA-sequencing. I hypothesized, that a simple yet modular set of genes was involved in wing pattern development of the skipper, similar to that of nymphalid butterflies and that genes such as WntA and Ubx would be differentially expressed as in nymphalids. ISH confirmed the presence of two Wnt genes and RNA-seq provided evidence of differential expression, suggesting that the genes underlining wing pattern diversity are being shared between these two distantly related families....