7 research outputs found
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The curious case of the camelthorn: competition, coexistence and nest-site limitation in a multispecies mutualism
Myrmecophyte plants house ants in domatia in exchange for protection from herbivores. Ant-myrmecophyte mutualisms exhibit two general patterns due to competition between ants for plant occupancy: i) domatia nest-sites are a limiting resource and ii) each individual plant hosts one ant species at a time. However, individual camelthorn trees (Vachellia erioloba) typically host two to four ant species simultaneously, often coexisting in adjacent domatia on the same branch. Such fine-grain spatial coexistence brings into question the conventional wisdom on ant-myrmecophyte mutualisms. Camelthorn ants appear not to be nest-site limited, despite low abundance of suitable domatia, and have random distributions of nest-sites within and across trees. These patterns suggest a lack of competition between ants for domatia and contrast strongly with other ant-myrmecophyte systems. Comparison of this unusual case with others suggests that spatial scale is crucial to coexistence or competitive exclusion involving multiple ant species. Furthermore, coexistence may be facilitated when co-occurring ant species diverge strongly on at least one niche axis. Our conclusions provide recommendations for future ant-myrmecophyte research, particularly in utilising multispecies systems to further our understanding of mutualism biology
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Pet cats (Felis catus) from urban boundaries use different habitats, have larger home ranges and kill more prey than cats from the suburbs
The domestic cat (Felis catus) is a predator of global significance. In Great Britain there are ca. 9.5 million owned pet cats, with their population determined by human population density. As urban areas expand and encroach on areas of conservation value, it is not known how cats use these areas and how habitat availability influences predation rates. To address this, over a year we recorded the movement and prey of 79 owned cats in inner suburban areas (non-boundary cats) and in areas adjacent to natural habitats on the edge of the suburban area (boundary cats). Boundary cats had larger home ranges (mean 3.42 S.E. ± 0.61 ha) and returned more prey (mean 7.91 S.E. ± 2.70 prey cat-1year−1) than cats in non-boundary areas (2.01 S.E. ± 0.70 ha; 3.35 S.E. ± 1.06 prey cat-1year-1respectively). Assuming a prey return rate of 23%, extrapolated predation rates equate to 34.40 (S.E. ± 11.74) and 14.57 (S.E. ± 4.62) prey cat-1year−1 in our boundary and suburban study sites respectively. While non-boundary cats had little access to natural habitats, natural habitats made up > 25% of the home range of boundary cats. Boundary cats travelled a mean distance of 64.9 m (S.E. ± 6.8) into these natural habitats, with some cats ranging > 300 m inside these areas. Bird predation rates did not differ between boundary and non-boundary cats, but boundary cats killed three times more mammals. This is of relevance to urban planning, as the hunting behaviour of pet cats extends the ecological effects of urbanisation into surrounding habitats
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Acceptance of near-natural greenspace management relates to ecological and socio-cultural assigned values among European urbanites
Grasslands are widespread elements of urban greenspace providing recreational, psychological and aesthetic benefits to city residents. Two urban grassland types of contrasting management dominate urban greenspaces: frequently mown, species-poor short-cut lawns and less intensively managed, near-natural tall-grass meadows. The higher conservation value of tall-grass meadows makes management interventions such as converting short-cut lawns into tall-grass meadows a promising tool for urban biodiversity conservation. The societal success of such interventions, however, depends on identifying the values urban residents assign to different types of urban grasslands, and how these values translate to attitudes towards greenspace management. Using 2027 questionnaires across 19 European cities, we identify the assigned values that correlate with people’s personal greenspace use and their preferences for different types of urban grasslands to determine how these values relate to the agreement with a scenario of converting 50% of their cities’ short-cut lawns into tall-grass meadows. We found that most people assigned nature-related values, such as wildness, to tall-grass meadows and utility-related values, such as recreation, to short-cut lawns. Positive value associations of wildness and species richness with tall-grass meadows, and social and nature-related greenspace activities, positively correlated with agreeing to convert short-cut lawns into tall-grass meadows. Conversely, disapproval of lawn conversion correlated with positive value associations of cleanliness and recreation potential with short-cut lawns. Here, people using greenspaces for nature-related activities were outstandingly positive about lawn conversion. The results show that the plurality of values assigned to different types of urban grasslands should be considered in urban greenspace planning. For example, tall-grass meadows could be managed to also accommodate the values associated with short-cut lawns, such as tidiness and recreation potential, to support their societal acceptance
Global urban environmental change drives adaptation in white clover
Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural clines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale