scholarly journals Gorgonians Are Foundation Species on Sponge-Dominated Mesophotic Coral Reefs in the Caribbean

2021 ◽  
Vol 8 ◽  
Author(s):  
Marc Slattery ◽  
Michael P. Lesser

Foundation species (FS) regulate ecological processes within communities often facilitating biodiversity and habitat complexity. Typically FS are dominant structure-forming taxa; but less dominant taxa having disproportionate ecological impacts to the community can also be FS. Mesophotic coral ecosystems (MCEs) are deep coral reef (∼30–150 m) communities, often dominated by emergent sponges in the Caribbean Basin. Despite the potential competitive advantage of sponges on MCEs, gorgonians are also common constituents of these reefs. Data from the Bahamas demonstrate increased biodiversity and densities of sponges on mesophotic reefs with gorgonians relative to reefs without these species. Drawing upon fifteen years of field surveys at five sites in the Caribbean Basin we assessed in situ interactions between gorgonians and sponges to quantify outcomes consistent with competition (i.e., tissue necrosis and overgrowth). Gorgonians were effective competitors against a variety of sponges, and two allelochemicals produced by Ellisella elongata were mechanistically important in interactions with Agelas clathrodes. We also examined invertebrate recruitment patterns near gorgonians to assess their role in facilitating MCE biodiversity. Our results indicate that live gorgonians, Antillogorgia bipinnata and E. elongata, facilitate biodiverse recruitment into MCEs, indicating that this process is governed by more than passive hydrodynamics. Collectively, these data indicate that these gorgonians exhibit both positive and negative ecological interactions (i.e., facilitation and competition, respectively) with sponges, and other taxa. Thus, these gorgonians are FS of MCE communities within the Caribbean Basin that display several traits contributing to the ecological structure of these understudied communities.

2018 ◽  
Vol 151 (1) ◽  
pp. 61-76
Author(s):  
Virginia Rebolledo Camacho ◽  
Lev Jardón Barbolla ◽  
Ivón Ramírez Morillo ◽  
Alejandra Vázquez-Lobo ◽  
Daniel Piñero ◽  
...  

Background – Pinus caribaea Morelet comprises three varieties of tropical pines distributed in the Caribbean Basin: P. caribaea var. hondurensis, var. caribaea, and var. bahamensis. The insular and continental distribution of these varieties, as well as the geological processes in the region, have been important factors for analysing evolutionary processes implicated in the diversification of these lineages. In this study, we evaluate the genetic and geographic structure within and between these three varieties in order to infer the possible origin and dispersal routes of these taxa.Methods – We used six polymorphic nuclear microsatellites (nSSR) in fifteen representative populations of the three pine varieties, sampled throughout their natural range in Central America, Cuba and the Bahamas islands.Results – The varieties contain similar levels of genetic variation (mean He = 0.571), with several populations out of Hardy-Weinberg equilibrium, and significant levels of inbreeding (0.097–0.184, P ≤ 0.05). A slight but significant genetic differentiation was found between the varieties (RST = 0.088) and populations (RST= 0.082), and genetic differentiation increased with geographic distance (r2 = 0.263). Distance and Bayesian BAPS analyses generated seven groups; two represented by the two island varieties and the remainder by the Central American populations of var. hondurensis. Migration rate estimates between pairs of groups ranged from M = 0.47 to M = 20.16. Estimates were generally higher from the continent to islands, with the highest migration rate estimated from a continental genetic group to the Cuba island group of var. hondurensis (M = 20.16).Conclusions – This study supports the hypothesis of a recent origin of these pine taxa through the migration of an ancestor from Central America, where the historical demography is associated with events of colonization, expansion and contraction of populations. The genetic variation and differentiation suggest that the three varieties are divergent lineages that currently share allelic variants, indicating that their speciation has not yet completed.


1989 ◽  
Author(s):  
Kenneth R. Walters ◽  
Andrew G. Korik ◽  
Michael J. Vojtesak

Author(s):  
Paula Schirrmacher ◽  
Christina C. Roggatz ◽  
David M. Benoit ◽  
Jörg D. Hardege

AbstractWith carbon dioxide (CO2) levels rising dramatically, climate change threatens marine environments. Due to increasing CO2 concentrations in the ocean, pH levels are expected to drop by 0.4 units by the end of the century. There is an urgent need to understand the impact of ocean acidification on chemical-ecological processes. To date, the extent and mechanisms by which the decreasing ocean pH influences chemical communication are unclear. Combining behaviour assays with computational chemistry, we explore the function of the predator related cue 2-phenylethylamine (PEA) for hermit crabs (Pagurus bernhardus) in current and end-of-the-century oceanic pH. Living in intertidal environments, hermit crabs face large pH fluctuations in their current habitat in addition to climate-change related ocean acidification. We demonstrate that the dietary predator cue PEA for mammals and sea lampreys is an attractant for hermit crabs, with the potency of the cue increasing with decreasing pH levels. In order to explain this increased potency, we assess changes to PEA’s conformational and charge-related properties as one potential mechanistic pathway. Using quantum chemical calculations validated by NMR spectroscopy, we characterise the different protonation states of PEA in water. We show how protonation of PEA could affect receptor-ligand binding, using a possible model receptor for PEA (human TAAR1). Investigating potential mechanisms of pH-dependent effects on olfactory perception of PEA and the respective behavioural response, our study advances the understanding of how ocean acidification interferes with the sense of smell and thereby might impact essential ecological interactions in marine ecosystems.


Zootaxa ◽  
2021 ◽  
Vol 4938 (1) ◽  
pp. 145-147
Author(s):  
RUDOLF H. SCHEFFRAHN

Cryptotermes Banks, 1906 is the third most diverse kalotermitid genus worldwide after Glyptotermes Froggatt, 1897 and Neotermes Holmgren, 1911, with its greatest diversity found in the Neotropics (Krishna et al. 2013a). Furthermore, the greatest number of species of Cryptotermes are known from the Caribbean Basin (Scheffrahn & Křeček 1999, Casala et al. 2016, Scheffrahn 2019). Although Araujo (1977) and Bacchus (1987) list Cryptotermes domesticus (Haviland, 1898) from Trinidad (treated as mainland) and Panama, respectively, Scheffrahn & Křeček (1999) and Scheffrahn et al. (2009) doubt the existence of this Asian species in the New World. Without C. domesticus, the total extant Neotropical diversity of Cryptotermes is 29 endemic and three exotic species (Constantino 2020). 


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