Risk-Prone and Risk-Averse Foraging Strategies Enable Niche Partitioning in Two Diurnal Orb-Weaving Spider Species
Location
Culp Ballroom
Start Date
4-7-2022 9:00 AM
End Date
4-7-2022 12:00 PM
Poster Number
69
Faculty Sponsor’s Department
Biological Sciences
Name of Project's Faculty Sponsor
Thomas Jones
Competition Type
Competitive
Type
Poster Presentation
Project's Category
Biological Adaptation, Circadian Rhythms, Evolutionary Biology, Life Sciences, Ecology
Abstract or Artist's Statement
Niche partitioning is a major component in understanding community ecology and how different species divide limited environmental resources, enabling them to coexist. Temporal niche partitioning has been widely studied in a broad sense, such as in species that forage on similar nutritional sources dividing activity along diurnal and nocturnal classifications. Here, we approach this temporal niche partitioning with higher resolution to investigate partitioning between species within the same broad temporal and foraging niche. Two species of diurnal orb-weaving spiders (Araneae: Araneidae), Verrucosa arenata and Micrathena gracilis, both construct their orbs in spatially similar locations throughout the understory of deciduous forests in the morning, forage on flying insects throughout the day, and retreat in the evening. However, despite consisting of what appear to be roughly similar total lengths of adhesive silk in the capture spiral, overall orb structure is starkly different: V. arenata orbs are relatively large in diameter and sparse with capture threads; M. gracilis orbs, condensed in diameter and tightly coiled. What other differences might distinguish foraging strategy within this same niche? With extensive observation in their natural environment, we have found that these two species employ two distinct strategies by modulating behavior and orb structure: V. arenata construct orbs earlier in the day, resulting in a longer foraging period. However, V. arenata webs are more likely to be destroyed during the day such that there is a higher variance in foraging duration in V. arenata. We also found that V. arenata actively capture and consume more large prey and that M. gracilis more passively capture and consume small prey more reliably. These data suggest that these species have evolved different foraging strategies with V. arenata being risk-prone and M. gracilis being risk-averse. This study provides a more nuanced analysis of niche partitioning between species occupying otherwise similar temporal, habitat, and foraging niches.
Risk-Prone and Risk-Averse Foraging Strategies Enable Niche Partitioning in Two Diurnal Orb-Weaving Spider Species
Culp Ballroom
Niche partitioning is a major component in understanding community ecology and how different species divide limited environmental resources, enabling them to coexist. Temporal niche partitioning has been widely studied in a broad sense, such as in species that forage on similar nutritional sources dividing activity along diurnal and nocturnal classifications. Here, we approach this temporal niche partitioning with higher resolution to investigate partitioning between species within the same broad temporal and foraging niche. Two species of diurnal orb-weaving spiders (Araneae: Araneidae), Verrucosa arenata and Micrathena gracilis, both construct their orbs in spatially similar locations throughout the understory of deciduous forests in the morning, forage on flying insects throughout the day, and retreat in the evening. However, despite consisting of what appear to be roughly similar total lengths of adhesive silk in the capture spiral, overall orb structure is starkly different: V. arenata orbs are relatively large in diameter and sparse with capture threads; M. gracilis orbs, condensed in diameter and tightly coiled. What other differences might distinguish foraging strategy within this same niche? With extensive observation in their natural environment, we have found that these two species employ two distinct strategies by modulating behavior and orb structure: V. arenata construct orbs earlier in the day, resulting in a longer foraging period. However, V. arenata webs are more likely to be destroyed during the day such that there is a higher variance in foraging duration in V. arenata. We also found that V. arenata actively capture and consume more large prey and that M. gracilis more passively capture and consume small prey more reliably. These data suggest that these species have evolved different foraging strategies with V. arenata being risk-prone and M. gracilis being risk-averse. This study provides a more nuanced analysis of niche partitioning between species occupying otherwise similar temporal, habitat, and foraging niches.