Patch size drives colonization by aquatic insects, with minor priority effects of a cohabitant

• Published in: Ecology and evolution 2021-12, Vol.11 (23), p.16817-16834
• Main Authors: Scott, Reed C., Pintar, Matthew R., Resetarits, William J.
• Format: Article
• Language: English
• Subjects: Aquatic insects; Biodiversity; Colonization; community assembly; Community structure; Competition; Density; Endangered & extinct species; Experiments; Geographical distribution; habitat selection; Habitats; Hypotheses; Immigration; Insects; Larvae; Mesocosms; patch size; priority effects; Shape effects; Species; water beetles
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.8313

Patch size is one of the most important factors affecting the distribution and abundance of species, and recent research has shown that patch size is an important niche dimension affecting community structure in aquatic insects. Building on this result, we examined the impact of patch size in conjunction with presence of larval anurans on colonization by aquatic insects. Hyla chrysoscelis (Cope's gray treefrog) larvae are abundant and early colonists in fishless lentic habitats, and these larvae can fill multiple ecological roles. By establishing larvae in mesocosms prior to colonization, we were able to assess whether H. chrysoscelis larvae have priority effects on aquatic insect assemblages. We conducted a series of three experiments in naturally colonized experimental landscapes to test whether (1) H. chrysoscelis larval density affects insect colonization, (2) variation in patch size affects insect colonization, and (3) the presence and larval density of H. chrysoscelis shift colonization of insects between patches of different size. Larval density independently had almost no effect on colonization, while patch size had species‐specific effects consistent with prior work. When larvae and patch size were tested in conjunction, patch size had numerous, often strong, species‐specific effects on colonization; larval density had effects largely limited to the assemblages of colonizing beetles and water bugs, with few effects on individual species. Higher larval densities in large mesocosms shifted some insect colonization to smaller patches, resulting in higher beta diversity among small patches in proximity to high density large mesocosms. This indicates establishing H. chrysoscelis larvae prior to insect colonization can likely create priority effects that slightly shape insect communities. Our results support the importance of patch size in studying species abundances and distributions and also indicate that colonization order plays an important role in determining the communities found within habitat patches. Patch size had strong effects on colonizing insect communities with some species preferring large patches and other species preferring small patches. Treefrog larvae have little direct effect on insect colonization, but when they had high densities in large patches, some of the insect colonization spilled over into adjacent small patches.