Environmental and ecological factors mediate taxonomic composition and body size of polyplacophoran assemblages along the Peruvian Province

Abstract

Intertidal communities’ composition and diversity usually exhibit strong changes in relation to environmental gradients at different biogeographical scales. This study represents the first comprehensive diversity and composition description of polyplacophoran assemblages along the Peruvian Province (SE Pacific, 12°S–39°S), as a model system for ecological latitudinal gradients. A total of 4,775 chitons from 21 species were collected on twelve localities along the Peruvian Province. This sampling allowed us to quantitatively estimate the relative abundance of the species in this assemblage, and to test whether chitons conform to elementary predictions of major biogeographic patterns such as a latitudinal diversity gradient. We found that the species composition supported the division of the province into three ecoregional faunal groups (i.e. Humboldtian, Central Chile, and Araucanian). Though chiton diversity did not follow a clear latitudinal gradient, changes in species composition were dominated by smaller scale variability in salinity and temperature. Body size significantly differed by ecoregions and species, indicating latitudinal size-structure assamblages. In some localities body size ratios differed from a random assemblage, evidencing competition at local scale. Changes in composition between ecoregions influence body size structure, and their overlapping produce vertical size segregation, suggesting that competition coupled with environmental conditions structure these assemblages.

Species That Fly at a Higher Game: Patterns of Deep–Water Emergence Along the Chilean Coast, Including a Global Review of the Phenomenon

“…In general, the statistical analyses searching for correlations between species distribution and seven environmental parameters (Supplementary Figure 8) suggest that several of these factors (primary production, salinity, oxygen and temperature, see Table 6 and Supplementary Figures 3-7, 8A,B,D,E) were significantly associated to the bathymetric distribution of the studied taxa of benthic invertebrates, but temperature was the most important environmental driver (Supplementary Figure 8D). In the intertidal areas of northern and central Chile species composition, abundance and diversity are influenced by temperature and salinity (Broitman et al, 2001(Broitman et al, , 2011Rivadeneira et al, 2002;Ibáñez et al, 2019). This study shows the same pattern at deep-sea communities (below the OMZ), where bottom temperature and salinity have a strong influence on bathymetric distribution.…”

Body size variation in polyplacophoran molluscs: Geographical clines and community structure along the south‐eastern Pacific

“…While spatial autocorrelation might contribute to this pattern as communities at mid latitudes often include the same species, we contend that interspecific competition could explain not only the positive relationship between these variables but also the higher diversity observed at mid latitudes (Mouquet et al., 2003; Shurin & Allen, 2001). The chiton species studied here vary in their diet and abundance (Aguilera & Navarrete, 2007; Aguilera et al, 2015; Camus et al., 2008; Ibáñez, Waldisperg, et al., 2019; Otaíza & Santelices, 1985), and some of them also exhibit local segregation in the intertidal habitat, in part associated with competition for space (e.g. shelters) and food (e.g.…”

“…niger inhabit the low intertidal under direct exposure in the surf zone, whereas smaller species such as Calloplax vivipara , Ischnochiton pusio and I . stramineus inhabit intertidal pools, under boulders and rocks (Araya & Araya, 2015; Ibáñez, Waldisperg, et al., 2019; Otaíza & Santelices, 1985). Interestingly, this segregation is often mirrored by differences between species in their tolerance to desiccation stress, as it varies considerably with microhabitat availability: species that inhabit medium and high intertidal zones have a greater tolerance to desiccation, osmotic stress and salinity than species that live close to the low tide line (Boyle, 1967; Harper & Williams, 2001; McMahon et al., 1991).…”

“…In addition, for marine vertebrates and invertebrates it has been evidenced that body size distribution shows a correlation with species richness at different spatial scales (Barneche et al., 2019; Labra et al., 2015). Particularly along the south‐east Pacific coast (SEP), latitudinal clines of body size have been detected at intraspecific level in several invertebrates (Camus et al., 2012; Ibáñez, Waldisperg, et al., 2019; Jaramilllo et al, 2017; Lardies et al., 2010; Sepúlveda et al., 2016). At community level, clear trends in species richness at latitudinal range have also been observed for different taxa in this geographical area (Aguilera et al., 2019; Cruz‐Motta et al., 2020; Ibáñez, Waldisperg, et al., 2019; Moreno et al., 2008; Navarrete et al., 2020; Rivadeneira et al., 2011; Valdovinos et al., 2003), suggesting a functional link between richness and body size.…”

First comparative assessment of the reproductive cycle of three species of Chiton on a temperate rocky shore of the southeastern Pacific

“…Along the southeastern Pacific (SEP) coast, chitons are also common, and several species exhibit broad geographic distributions, occurring in numerous ecoregions and in more than one biogeographical province (Ibáñez et al., 2019). Only recently have chitons been subject to more detailed studies, which have focused mainly on their cytogenetics (Northland‐Leppe et al., 2010), ecology (e.g., Aguilera & Navarrete, 2007, 2012; Camus et al., 2008, 2012; Ibáñez et al., 2016; Ibáñez et al., 2019; Sanhueza et al., 2008), taxonomic records (Araya & Araya, 2015; Sanhueza & Ibáñez, 2016; Tobar‐Villa & Ibáñez, 2013), or morphometric and allometric variations (Ibáñez et al., 2018; Torres et al., 2018). Despite these recent advances, the reproductive cycles of most species remain unknown or poorly understood.…”