Browsing by Author "Robinson, Kristin"

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    Araneae Biodiversity in the Ecuadorian Chocó: Impact of Altitude and Land Use on Spider Diversity
    (2018) Robinson, Kristin
    The Tumbes-Chocó-Magdalena bioregion in the Ecuadorian Andes is one of the most biodiverse areas in the world. This ecosystem is threatened primarily by deforestation and climate change. Spiders are surprisingly very understudied in this area of the world considering their diversity, their importance as bioindicators, and the threats facing their habitats. The objectives of this study were to discover which families and genera of spiders are found within the La Hesperia reserve, to understand how altitude affects spider diversity, and to investigate differences in spider communities based on land use. Four nocturnal visual transects, 150m by 4m, at various elevations (1200.7m, 1367m, 1371.3m, 1501m) were each sampled for three days by macro-photographing spiders. The total data collection spanned 12 days and resulted in 1,318 individuals in 16 families, 33 genera, and 188 morphospecies. The most abundant families were Theridiidae (n=624, 47.2%), Araneidae (n=322, 24.4%), then Ctenidae, Pholcidae, Anyphaenidae, and other less common families. Guilds were assigned based on foraging strategy. The orb web guild (Araneidae, Tetragnathidae, Uloboridae, Synotaxidae) was the most diverse while the space web guild (Theridiidae, Pholcidae) was the most abundant but one of the least diverse. The transect with mild land use, a small bamboo plantation, nearby was more diverse than the other transect at the same elevation. The mild disturbance likely allowed for more vegetation complexity, therefore, more diversity. The 1501m transect was the least diverse and had the highest abundance of the space web guild. Diversity of spiders can increase with mild disturbance, spider diversity generally tends to decrease with elevation, and subsocial spiders are more common at higher elevations compared to low elevation social spiders.
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    Araneae Biodiversity in the Ecuadorian Chocó: Impact of Altitude and Land Use on Spider Diversity
    (2019) Robinson, Kristin; Silva, Xavier
    In the neotropical cloud forests, spiders are severely understudied despite their diversity, importance as bioindicators, and threats facing their habitat. The Tumbes-Chocó-Magdalena bioregion in the Ecuadorian Andes is one of the most biodiverse areas in the world. This ecosystem is threatened by agricultural deforestation and climate change that disproportionately affect mountainous biomes. The objectives of this study were to investigate 1) which spider genera are found within the private reserve, La Hesperia Reserva Natural; 2) how elevation affects spider diversity; and 3) how land use affects spider diversity. Four nocturnal visual transects (150m long) at three elevations were sampled via macro-photography. Over 12 days, 1,318 individuals in 16 families, 33 genera, and 188 morphospecies were identified. The most abundant families were Theridiidae (n=624, 47.2%), Araneidae (n=322, 24.4%), and Ctenidae (n=87, 6.6%). Families were assigned to guilds based on hunting strategy. The orb web guild (Araneidae, Tetragnathidae, Uloboridae, Synotaxidae) was most diverse while the space web guild (Theridiidae, Pholcidae) was most abundant but one of the least diverse due to the disproportionate abundance of one subsocial species in the Theridion genus. The transect with mild land use was the most diverse possibly due to more complex vegetation, however, this is not definitive due to lack of replicates. This study established a baseline spider biodiversity survey of La Hesperia Reserva Natural, and the findings support the hypotheses that spider diversity is found to generally decrease with increasing elevation, and subsocial spiders are found to be more common at higher elevations.