Species assemblages of insular Caribbean Sticta (lichenized Ascomycota: Peltigerales) over ecological and evolutionary time scales.

Phylogenetic approaches to macroevolution have provided unique insight into evolutionary relationships, ancestral ranges, and diversification patterns for many taxa. Similar frameworks have also been developed to assess how environmental and/or spatial variables shape species diversity and distribution patterns at different spatial/temporal scales, but studies implementing these are still scarce for many groups, including lichens. Here, we combine phylogeny-based ancestral range reconstruction and diversification analysis with community phylogenetics to reconstruct evolutionary origins and assess patterns of taxonomic and phylogenetic relatedness between island communities of the lichenized fungal genus Sticta in the Caribbean. Sampling was carried out in the Greater Antilles (Cuba, Jamaica, Dominican Republic, and Puerto Rico) and Lesser Antilles (Dominica, Guadeloupe, and Martinique). Data for six molecular loci were obtained for 64 candidate Caribbean species and used to perform both macroevolutionary phylogenetics, which also included worldwide taxa, and phylobetadiversity analyses, which emphasized island-level communities. Our work uncovered high levels of island endemism (∼59%) in Caribbean Sticta. We estimate initial colonization of the region occurred about 19 Mya from a South American ancestor. Reverse migration events by Caribbean lineages to South America were also inferred. We found no evidence for increased diversification rates associated with range expansion into the Caribbean. Taxonomic and phylogenetic turnover between island-level communities was most strongly correlated with environmental variation rather than with geographic distance. We observed less dissimilarity among communities from the Dominican Republic and Jamaica than between these islands and the Lesser Antilles/Puerto Rico. High levels of hidden diversity and endemism in Caribbean Sticta reaffirm that islands are crucial for the maintenance of global biodiversity of lichenized fungi. Altogether, our findings suggest that strong evolutionary links exist between Caribbean and South American biotas but at regional scales, species assemblages exhibit complex taxonomic and phylogenetic relationships that are determined by local environments and shared evolutionary histories.

Digestive enzymes of two freshwater fishes (Limia vittata and Gambusia punctata) with different dietary preferences at three developmental stages.

The variation of activity of some digestive enzymes was studied in three age groups of two freshwater endemic fishes from Cuba: Limia vittata and Gambusia punctata. Trypsin, chymotrypsin and amylase activities showed a different pattern between both species. Trypsin and chymotrypsin activity increased with the age of fishes, while amylase activity decreased. The highest activity of trypsin and chymotrypsin was registered in G. punctata while the highest amylase activity was detected in L. vittata. Zymograms revealed proteases with molecular masses similar to trypsin and chymotrypsin reported for other fish species. Amylase electrophoresis showed the presence of this enzyme; in L. vittata amylase zymograms showed two bands with molecular masses of 175 and 100 kDa and in G. punctata four bands of 175, 100, 46 and 30 kDa respectively were found. The activity of the digestive enzymes can be used as an effective indicator of the feeding habits and the development of the digestive tracts in L. vittata and G. punctata.