Multi‐scale and antagonist selection on life‐history traits in parasitoids: A community ecology perspective

Abstract

Life‐history traits within ecological communities can be influenced by regional environmental conditions (external filters) and community‐wide density‐dependent processes (internal filters). While traits in a regional context may converge to a narrow range of values because of environmental filtering, species belonging to a guild may present contrasting traits as a means of niche differentiation, allowing coexistence whilst exploiting the same resources. To disentangle the role of external and internal filters on phenotypic diversity within ecological communities, we examined the patterns of life‐history trait variation within a guild of insect parasitoids during two successive years across three contrasted regions in relation to several ecological factors. By combining a mean‐field approach and an analysis of phenotypic variance across organizational levels (from individual to guild), we showed that the patterns of life‐history trait variation across regions are consistent with local adaptation or adaptive phenotypic plasticity while the patterns of phenotypic variation within regions suggested how coexistence modulates life‐history traits expression through niche differentiation. Within a given region, phenotypic pattern of parasitoid life‐history traits may also arise from bottom‐up effects of trophic webs: insect host species could also control parasitoid life‐history traits in nature. Our results also showed that parasitoid life‐history traits presented contrasting variation patterns according to the sampling year, suggesting temporal variations in evolutionary and ecological dynamics of parasitoid species. The application of such trait‐based studies to insect parasitoids has the potential to provide further insight on how agricultural environments contribute to differential diversification among natural enemies guilds, highlighting the main role of agricultural landscape management for organisms'responses. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13007/suppinfo is available for this article.

Intraspecific trait variability and community assembly in hawkmoths (Lepidoptera: Sphingidae) across an elevational gradient in the eastern Himalayas, India

“…The large elevational range of 3,150 m coupled with high rainfall (>3,000 mm along the southern slopes) has resulted in diverse habitat types ranging from tropical wet evergreen below 900 m to coniferous temperate forests above 2,700 m (Champion & Seth, 1968). The high diversity of this region, believed to be due to its complex terrain and its location at the confluence of the Oriental and Sino-Japanese floristic and faunistic zones (Holt et al, 2013), makes it a globally important biodiversity hot spot (Orme et al, 2005).…”

“…The eastern Himalayas are among the most biologically diverse regions in the world (Myers et al, 2000;Orme et al, 2005). Its large environmental gradient and biodiversity (of which moths are a prime example) make an excellent combination for investigating the link between environment and diversity.…”

“…Additionally, one can test for deviation of the measured values of the metrics from those expected from randomness. Significant deviation from randomness is considered evidence of the impact of an ecological process on the trait distribution (Danet et al., 2018; Gusmão et al., 2020; Khalil et al., 2019; Luo et al., 2016; Neyret et al., 2016; Outreman et al., 2018; Subedi et al., 2019; Xavier‐Jordani et al., 2019; Zorger et al., 2019).…”

“…Community assembly studies using T‐statistics require trait measurements of (many) individuals of a species and therefore have mostly targeted plants with only a small number of faunal studies: aphid parasitoids (Outreman et al., 2018), spiders (Gusmão et al., 2020), moths (Wu et al., 2019), and amphibians (Xavier‐Jordani et al., 2019). The relationship between traits and their functionality is more easily quantifiable in plants, and the traits are more easily measured for a large number of individuals (Lamanna et al., 2014; Lavorel et al., 2013), than is the case with faunal taxa (Brousseau et al., 2018).…”

How climate change affects the seasonal ecology of insect parasitoids

“…With climate changes, we expect traits linked to overwintering strategies to become more convergent among parasitoid species because of increasing environmental filtering at the community level (i.e. warmer temperatures leading to diapause avoidance) (Le Lann et al, 2014b;Outreman et al, 2017). By contrast, traits are expected to diverge in communities where niche partitioning favours high levels of competition (MacArthur & Levins, 1967) and leads to the formation of populations/communities with both diapausing and non-diapausing individuals/species.…”