J Wasserman results 43
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Assessing biological invasion predatory impacts through interaction strengths and morphological trophic profilingNARA Subscribed
Biological invasions are a major stressor on ecosystems worldwide, but tools to predict their predatory impact remain limited. Here, we quantified invader impacts using two complementary approaches: functional responses (to reveal per capita and multiple predator interaction strengths) and ecomorphology (to reveal trophic profiles and competitive overlap). We compared Mozambique tilapia Oreochromis mossambicus, a native southe...
Salinisation of arid temporary pools alters crustacean hatching success but not phenology dynamicsNARA Subscribed
The widespread acceleration of freshwater salinisation due to human activities, such as pollution, resource extraction and urbanisation coupled with climate change, poses a significant threat to aquatic ecosystems. Limited work has been directed towards salinisation effects in temporary wetland systems. These systems are characterised by unique crustacean communities reliant on dormant egg production. We assessed salinisation...
Refuge‐yeah or refuge‐nah? Predicting locations of forest resistance and recruitment in a fiery worldNARA Subscribed
Climate warming, land use change, and altered fire regimes are driving ecological transformations that can have critical effects on Earth's biota. Fire refugia—locations that are burned less frequently or severely than their surroundings—may act as sites of relative stability during this period of rapid change by being resistant to fire and supporting post‐fire recovery in adjacent areas. Because of their value to forest ecosy...
The analysis of food web structures has increased the understanding of the dynamics of organisms belonging to different trophic levels. In this study, the diet of two native species, Glossogobius callidus and Gilchristella aestuaria , was assessed in the presence of two non‐native species, Oreochromis mossambicus and Gambusia affinis , in irrigation ponds, Eastern Cape Province, South Africa. The proportion of dietary items co...
Parallel evolution is considered strong evidence for natural selection. However, few studies have investigated the process of parallel selection as it plays out in real time. The common approach is to study historical signatures of selection in populations already well adapted to different environments. Here, to document selection under natural conditions, we study six populations of threespine stickleback ( Gasterosteus acule...
Invasive alien species impacts might be mediated by environmental factors such as climatic warming. For invasive predators, multiple predator interactions could also exacerbate or dampen ecological impacts. These effects may be especially pronounced in highly diverse coastal ecosystems that are prone to profound and rapid regime shifts. We examine emergent effects of warming on the strength of intraspecific multiple predator e...
The river goby Glossogobius callidus is native to freshwater and estuarine habitats in South Africa. Individuals [21.1–144.4 mm total length ( L T )] were sampled from impoundments in the Sundays River Valley, Eastern Cape, from February 2014 to March 2015. The largest female was 137.2 mm L T , and the largest male was 144.4 mm L T . Length‐at‐50% maturity was 75.2 ± 2.1 mm L T for males and 76.2 ± 2.0 mm L T for females. Abso...
Assessing multiple predator, diurnal and search area effects on predatory impacts by ephemeral wetland specialist copepodsNARA Subscribed
Predator–prey interaction strengths can be highly context-dependent. In particular, multiple predator effects (MPEs), variations in predator sex and physical habitat characteristics may affect prey consumption rates and thus the persistence of lower trophic groups. Ephemeral wetlands are transient ecosystems in which predatory copepods can be numerically dominant. We examine the interaction strengths of a specialist copepod Pa...
Sex demographics alter the effect of habitat structure on predation by a temporary pond specialistNARA Subscribed
Habitat structure can profoundly influence interaction strengths between predators and prey. Spatio-temporal habitat structure in temporary wetland ecosystems is particularly variable because of fluctuations in water levels and vegetation colonisation dynamics. Demographic characteristics within animal populations may also alter the influence of habitat structure on biotic interactions, but have remained untested. Here, we inv...