Title

Population, Community, and Metacommunity Dynamics of Terrestrial Gastropods in the Luquillo Mountains: a Gradient Perspective

Publication Date

2013

Document Type

Book Chapter

Abstract

Elevational variation in the Luquillo Mountains creates strong environmental gradients that affect the abundance and distribution of species. Moreover, the geographic mappings of these environmental gradients will likely shift as a consequence of global climate change, subsequently altering patterns of biodiversity. Because they are taxonomically diverse, numerically abundant, responsive to anthropogenic and natural disturbances, and potentially keystone heterotrophs (detritivores, herbivores, and carnivores), terrestrial gastropods represent a model taxon for exploring variation in biodiversity. As a consequence, we synthesize extant knowledge and execute new analyses to explore spatial and environmental variation in multiple aspects of gastropod biodiversity at the population (total abundance as well as abundance of each of 14 species), community (richness, evenness, dominance, rarity, diversity), and meta-community levels. Mean elevational range size of species increased with increasing elevation, but provided only weak support for the elevational extension of Rapoport’s rule. The abundances of most species varied with elevation, and did so in a consistent manner along mixed forest (tabonuco – palo colorado – elfin forest) and palm forest transects. Similarly, community level aspects of biodiversity varied with elevation in a consistent manner in both mixed forest and palm forest transects. Moreover, variation among sites in species composition was similar regardless of whether the ordination was based on incidence (i.e. presence versus absence of species) or abundance (double square root transformed density). This was true for the mixed forest as well as for the palm forest transects. In addition, variation among sites in composition was correlated with elevation. Finally, based on analyses of coherence, range turnover, and boundary clumping, metacommunity structure along the mixed forest transect was Clementsian, whereas along the palm forest transect it was quasi-Gleasonian. Population- and community-level attributes of biodiversity changed gradually, and paralleled variation in total gastropod abundance and net primary productivity in general. Similar mechanisms (more individuals hypothesis or passive sampling) explain both elevational variation and the differences between mixed forest and palm forest transects. Moreover, the higher abundances of gastropods in palm-dominated forest patches is a likely mechanism contributing to differences between metacommunity organization in the mixed forest and palm forest transects.

Original Citation

Willig, M.R., Presley, S.J., Bloch, C.P., & Alvarez, J. (2013). Population, Community, and Metacommunity Dynamics of Terrestrial Gastropods in the Luquillo Mountains: a Gradient Perspective. In G. Gonzalez, M.R. Willig, & R.B. Waide (Eds.), Ecological Gradient Analyses in a Tropical Landscape (Ecological Bulletins 54), (pp. 117-140). Oxford: John Wiley & Sons.

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