RESUMO
We provide an update, based on literature records, on biodiversity and distribution of echinoderms along the state of Santa Catarina, Brazil. Sixty-one echinoderms taxa are reported, in 36 families. We present information on habitat distribution, taxonomy and possible threats to these species. The highest number of echinoderm records was between 25°19'S and 28°11'S latitudes, and sites of the Continental Shelf and the Reserva Biológica Marinha of Arvoredo area had the most species records (30 and 26 species, respectively). In addition, Santa Catarina is the southernmost record, in the Atlantic Ocean, for 40 echinoderm species; of these, 10 are on the regional list of endangered species. Eight species are endemic to Brazil and one ophiuroid species was reported herein for the first time at Santa Catarina: Ophiacantha pentacrinus Lütken, 1869.(AU)
Assuntos
Animais , Espécies em Perigo de Extinção , Biodiversidade , Equinodermos/classificação , Distribuição AnimalRESUMO
An updated molecular phylogeny of the blenny genus Ophioblennius, with a focus on two geographically disjunct morphotypes observed in Brazil, is presented. The analyses showed that specimens from the north-eastern Brazilian coast are the endemic redlip blenny Ophioblennius trinitatis, but specimens from the southern Brazilian coast are conspecific to an undescribed east Atlantic Ocean (Gulf of Guinea) species, previously unknown in Brazil. Possible explanations for this geographical pattern include: natural larval dispersal and rafting across the Atlantic; an unknown ecological attribute that enabled this species to colonize southern Brazil; oil platforms as introduction vectors.
Assuntos
Perciformes , Filogenia , Animais , Oceano Atlântico , Brasil , Geografia , FilogeografiaRESUMO
The disparity in species richness among evolutionary lineages is one of the oldest and most intriguing issues in evolutionary biology. Although geographical factors have been traditionally thought to promote speciation, recent studies have underscored the importance of ecological interactions as one of the main drivers of diversification. Here, we test if differences in species richness of closely related lineages match predictions based on the concept of density-dependent diversification. As radiation progresses, ecological niche-space would become increasingly saturated, resulting in fewer opportunities for speciation. To assess this hypothesis, we tested whether reef fish niche shifts toward usage of low-quality food resources (i.e. relatively low energy/protein per unit mass), such as algae, detritus, sponges and corals are accompanied by rapid net diversification. Using available molecular information, we reconstructed phylogenies of four major reef fish clades (Acanthuroidei, Chaetodontidae, Labridae and Pomacentridae) to estimate the timing of radiations of their subclades. We found that the evolution of species-rich clades was associated with a switch to low quality food in three of the four clades analyzed, which is consistent with a density-dependent model of diversification. We suggest that ecological opportunity may play an important role in understanding the diversification of reef-fish lineages.
Assuntos
Biodiversidade , Recifes de Corais , Dieta , Evolução Molecular , Peixes , Animais , FilogeniaRESUMO
Shallow-water tropical reefs and the deep sea represent the two most diverse marine environments. Understanding the origin and diversification of this biodiversity is a major quest in ecology and evolution. The most prominent and well-supported explanation, articulated since the first explorations of the deep sea, holds that benthic marine fauna originated in shallow, onshore environments, and diversified into deeper waters. In contrast, evidence that groups of marine organisms originated in the deep sea is limited, and the possibility that deep-water taxa have contributed to the formation of shallow-water communities remains untested with phylogenetic methods. Here we show that stylasterid corals (Cnidaria: Hydrozoa: Stylasteridae)--the second most diverse group of hard corals--originated and diversified extensively in the deep sea, and subsequently invaded shallow waters. Our phylogenetic results show that deep-water stylasterid corals have invaded the shallow-water tropics three times, with one additional invasion of the shallow-water temperate zone. Our results also show that anti-predatory innovations arose in the deep sea, but were not involved in the shallow-water invasions. These findings are the first robust evidence that an important group of tropical shallow-water marine animals evolved from deep-water ancestors.