Castro-Arellano, Ivan (2005-12). Ecological patterns of the small mammal communities at El Cielo Biosphere Reserve, Tamaulipas, Mexico. Doctoral Dissertation. Thesis uri icon

abstract

  • Scarce knowledge of Neotropical small mammal communities prevents experimental inquiry on the mechanisms structuring these communities. In this study, I examined patterns of local assembly of the small mammal communities on the eastern slopes of El Cielo Biosphere Reserve (ECBR) in Tamaulipas, Mexico, at two spatial scales. At the landscape level I tested patterns of species co-occurrences between four sites with a null model. At the local level I addressed floor microhabitat use, vertical structure use and temporal partitioning. I studied these niche axes at two adjoining forest types, Tropical Subdeciduous Forest (TSDF) and Cloud Forest (CF), that had different structural complexity. Total trapping effort consisted of 19,712 trapnights distributed over three years. In 1,365 capture events I recorded 789 individuals representing 14 species. Abundant species, mostly Peromyscus species that are of intermediate body size, co-occurred less often than expected by chance, whereas rare species, mainly Reithrodontomys species of small size, occurred at random over study sites. This pattern suggests that species interactions might be responsible for this non-random structure. Both the TSDF and CF had striking differences in both microhabitat use and temporal partitioning. In the TSDF common species (>8 individuals) organized along a microhabitat gradient from grassy/open areas to closed forest areas. Temporal partitioning for the whole community was less than expected by chance with use of an ad hoc null model. Species from ecotone/open areas avoided use of middle portions of the night whereas the single forest species concentrated activity in this period. So, it is plausible that predator avoidance strategies might have higher impact on temporal partitioning as compared to competitive interactions. In high contrast the CF community was codominated by two Peromyscus species that overlapped heavily in both their microhabitat use and diel activity patterns. Ecological separation of these two species probably occurs along a niche axis not considered in my study or might be facilitated by their body mass difference. Overall, I provide the first account of community patterns for small mammals at ECBR. These patterns can provide the basis for experimental manipulations to ascertain mechanisms responsible for structure at these communities.
  • Scarce knowledge of Neotropical small mammal communities prevents
    experimental inquiry on the mechanisms structuring these communities. In this study, I
    examined patterns of local assembly of the small mammal communities on the eastern
    slopes of El Cielo Biosphere Reserve (ECBR) in Tamaulipas, Mexico, at two spatial
    scales. At the landscape level I tested patterns of species co-occurrences between four
    sites with a null model. At the local level I addressed floor microhabitat use, vertical
    structure use and temporal partitioning. I studied these niche axes at two adjoining
    forest types, Tropical Subdeciduous Forest (TSDF) and Cloud Forest (CF), that had
    different structural complexity. Total trapping effort consisted of 19,712 trapnights
    distributed over three years. In 1,365 capture events I recorded 789 individuals
    representing 14 species. Abundant species, mostly Peromyscus species that are of
    intermediate body size, co-occurred less often than expected by chance, whereas rare
    species, mainly Reithrodontomys species of small size, occurred at random over study
    sites. This pattern suggests that species interactions might be responsible for this non-random structure. Both the TSDF and CF had striking differences in both microhabitat
    use and temporal partitioning. In the TSDF common species (>8 individuals) organized
    along a microhabitat gradient from grassy/open areas to closed forest areas. Temporal
    partitioning for the whole community was less than expected by chance with use of an
    ad hoc null model. Species from ecotone/open areas avoided use of middle portions of
    the night whereas the single forest species concentrated activity in this period. So, it is
    plausible that predator avoidance strategies might have higher impact on temporal
    partitioning as compared to competitive interactions. In high contrast the CF community
    was codominated by two Peromyscus species that overlapped heavily in both their
    microhabitat use and diel activity patterns. Ecological separation of these two species
    probably occurs along a niche axis not considered in my study or might be facilitated by
    their body mass difference. Overall, I provide the first account of community patterns
    for small mammals at ECBR. These patterns can provide the basis for experimental
    manipulations to ascertain mechanisms responsible for structure at these communities.

publication date

  • December 2005