Occupancy and environmental responses of habitat specialists and generalists depend on dispersal traits

Abstract

Abstract. Ecologists have been interested in understanding communities through the lens of specialists and generalists to predict species diversity and distribution patterns and to ameliorate worldwide declines in specialist species. Dispersal traits are assumed to be associated with specialization (specialists are weaker dispersers than generalists), but dispersal modes can be variable within groups. Niche-based predictions of occupancy and environmental responses were assessed using invertebrates from California vernal pools that were categorized by specialization (endemic or widespread taxa) and dispersal mode (passive or active dispersal). Data from a latitudinal gradient resulted in widespread taxa with greater percent occupancy than endemic taxa as predicted, but passive dispersers had greater occupancy than active dispersers in contrast to predictions. Endemic species and widespread-active dispersers exhibited similar levels of specialization measured as coefficient of variation among treatments in a mesocosm experiment. This suggested that habitat choice was important, and these differences in specialization were scale dependent (generalists across habitat types and specialists within a habitat type). A negative correlation between latitudinal occupancy and level of specialization demonstrated how local-scale responses and landscape patterns were related and depend on both specialization and dispersal traits. This study underscores how habitat heterogeneity and species traits, including specialization and dispersal, can interact to affect community patterns at different spatial scales.

Dormancy in Metacommunities

“…Additional evidence from microcrustaceans in California vernal pools (n p 787) suggests that dormancy affects regional patterns of diversity (Kneitel 2016(Kneitel , 2018. Among generalists in this system, passive dispersers with the ability to enter dormancy (ostracods, cladocerans, and copepods) have much higher site occupancy (150%) than active dispersers that lack dormancy (Kneitel 2018). Together, these examples show how dormancy can influence metacommunity structure and dynamics in spatiotemporally variable landscapes.…”

“…The seed bank allows early successional species to persist in the metacommunity even though they are often driven locally extinct by competitors and predators that colonize later via aerial dispersal (Vanschoenwinkel et al 2010). Additional evidence from microcrustaceans in California vernal pools (n p 787) suggests that dormancy affects regional patterns of diversity (Kneitel 2016(Kneitel , 2018. Among generalists in this system, passive dispersers with the ability to enter dormancy (ostracods, cladocerans, and copepods) have much higher site occupancy (150%) than active dispersers that lack dormancy (Kneitel 2018).…”

Livestock disturbances in Mediterranean temporary ponds: A mesocosm experiment with sheep manure and simulated trampling

“…As these taxa arrived in mesocosms from the surrounding landscape, habitat choice becomes an important factor in their distribution and abundance (e.g. Kneitel, 2018). Resource levels are known to influence oviposition behaviour of insects (Blaustein & Kotler, 1993;Srivastava & Lawton, 1998).…”

Effects of life‐history traits on stream fish abundances across spatial scales

“…abiotic features) factors (Bonada, Dolédec, & Statzner, ). Numerous studies of aquatic organisms have focused on the role of traits on spatial structure of species occurrence (Kneitel, ; Radinger & Wolter, ), synchrony of recruitment among sites through time (Bret, Bergerot, Capra, Gouraud, & Lamouroux, ; Cattanéo, Hugueny, & Lamouroux, ; Grenouillet, Hugueny, Carrel, Olivier, & Pont, ) and community properties (de Bie et al, ; Cañedo‐Argüelles et al, ; Grönroos et al, ). At the population level, most studies have been species‐specific and thus have limited utility for generalising across taxa.…”