scholarly journals Distributions of Invasive Arthropods across Heterogeneous Urban Landscapes in Southern California: Aridity as a Key Component of Ecological Resistance

Insects ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 29 ◽  
Author(s):  
Weston Staubus ◽  
Savanah Bird ◽  
Savannah Meadors ◽  
Wallace Meyer

Urban systems often support large numbers of non-native species, but due to the heterogeneity of urban landscapes, species are not evenly distributed. Understanding the drivers of ecological resistance in urban landscapes may help to identify habitats that are most resistant to invasion, and inform efforts to model and conserve native biodiversity. We used pitfall traps to survey non-native ground-dwelling arthropods in three adjacent, low-elevation habitat types in southern California: California sage scrub, non-native grassland, and suburban development. We found that non-native species were fewer and less widely distributed in the sage scrub and grassland habitats. Due to the proximity of our sites, differences in propagule pressure is an unlikely explanation. Instead, we suggest that the absence of water subsidies in the sage scrub and grassland habitats increases those habitats’ resistance to arthropod invasions. Comparisons to studies conducted at fragments closer to the coast provide further support for the relationship between aridity and invasibility in southern California. Our findings highlight that inland fragments are important for conserving native arthropod diversity, that models of non-native species distributions in arid and semi-arid urban systems should include aridity measures, and that reducing resource subsidies across the region is critical to mitigating spread of non-natives.

2019 ◽  
Vol 286 (1901) ◽  
pp. 20190036 ◽  
Author(s):  
Hanno Seebens ◽  
Elizabeta Briski ◽  
Sara Ghabooli ◽  
Tamara Shiganova ◽  
Hugh J. MacIsaac ◽  
...  

The number of released individuals, which is a component of propagule pressure, is considered to be a major driver for the establishment success of non-native species. However, propagule pressure is often assumed to result from single or few release events, which does not necessarily apply to the frequent releases of invertebrates or other taxa through global transport. For instance, the high intensity of global shipping may result in frequent releases of large numbers of individuals, and the complexity of shipping dynamics impedes predictions of invasion dynamics. Here, we present a mathematical model for the spread of planktonic organisms by global shipping, using the history of movements by 33 566 ships among 1477 ports to simulate population dynamics for the comb jelly Mnemiopsis leidyi as a case study. The degree of propagule pressure at one site resulted from the coincident arrival of individuals from other sites with native or non-native populations. Key to sequential spread in European waters was a readily available source of propagules and a suitable recipient environment. These propagules were derived from previously introduced ‘bridgehead’ populations supplemented with those from native sources. Invasion success is therefore determined by the complex interaction of global shipping and local population dynamics. The general findings probably hold true for the spread of species in other complex systems, such as insects or plant seeds exchanged via commercial trade or transport.


Plant Ecology ◽  
2019 ◽  
Vol 220 (2) ◽  
pp. 151-169 ◽  
Author(s):  
Chandler E. Puritty ◽  
Ellen H. Esch ◽  
Sherlynette Pérez Castro ◽  
Elizabeth M. Ryan ◽  
David A. Lipson ◽  
...  

2010 ◽  
Vol 16 (1) ◽  
pp. 36 ◽  
Author(s):  
A. J. Buckmaster ◽  
W. S. Osborne ◽  
N. Webb

Urban development can alter species composition and diversity within an area through biotic homogenization, the introduction of exotic species, and localized extinctions of native species. In this study we examined the composition and diversity of small terrestrial mammals within nature reserves surrounded by urban landscapes and compared this with previous surveys of these reserves and nearby non-urban reserves with similar vegetative and geomorphological characteristics. A combination of live trapping and indirect detection techniques was employed in eight reserves in the Australian Capital Territory and surrounding New South Wales to determine current species composition. Compared with previous studies and the non-urban reserves, the urban reserves appear to have lost two-thirds of their native terrestrial small mammal species in the past 26 years. Exotic species were present in all urban reserves, but were only associated with areas characterized by human-induced disturbance in non-urban reserves. Possible causes of this disparity in native species diversity between urban and non-urban reserves are discussed.


2003 ◽  
Vol 9 (2) ◽  
pp. 144 ◽  
Author(s):  
Lourraine A. Tigas ◽  
Dirk H. Van Vuren ◽  
Raymond M. Sauvajot

We investigated the responses of carnivores to habitat fragmentation in urban southern California. We used scat, track, and remote camera surveys to determine presence and residence of carnivores on habitat fragments of various sizes (4.4-561.0 ha) and degrees of isolation (10-750 m). Fragment area explained a significant portion of the variation in all four measures of species richness (total species present, native species present, total species resident, and native species resident). Isolation was of secondary importance and was significant only for species presence. We suggest that fewer carnivore species at smaller or more isolated fragments resulted from foraging decisions based on lower food reward in smaller fragments and greater movement costs for more distant fragments. Carnivore species responded differentially to fragmentation. Bobcats Lynx rufus were fragmentation-sensitive and apparently required large fragments, thus they may be useful as focal species for conservation planning. In contrast, Coyotes Canis latrans were more fragmentation-tolerant and, along with smaller species such as Northern Raccoons Procyon lotor, Striped Skunks Mephitis mephitis, and Virginia Opossums Didelphis virginiana, can persist in smaller fragments. Our results suggest that most of the common carnivores can persist in fragmented urban habitat, provided that fragments are sufficiently large and in close proximity.


1996 ◽  
Vol 30 (4) ◽  
pp. 1020-1045
Author(s):  
Jane R. Rubin-Kurtzman ◽  
Roberto Ham-Chande ◽  
Maurice D. Van Arsdol

This article is a case study of population growth and composition in the Southern California-Baja California trans-border urban system (TBS). The central question guiding the research is how the combination of geographic proximity and economic integration in two very different regions affects population characteristics in the Southern California-Baja California TBS. We begin by briefly defining trans-border urban systems. We then specify the attributes of the Southern California-Baja California TBS, contrasting them with attributes observed elsewhere in the United States and Mexico. We particularly emphasize the impact of the Mexican-origin population on population growth, composition, age structure and trans-border mobility. We conclude by outlining several national and international policy implications that can be derived from a regional focus on the Southern California-Baja California TBS. The units of analysis are the aggregate TBS and the component counties and municipios. The data are drawn primarily from the U.S. and Mexican censuses. Secondary data from a variety of sources also are discussed.


Hydrobiologia ◽  
2019 ◽  
Vol 847 (7) ◽  
pp. 1619-1629 ◽  
Author(s):  
Nayara Louback-Franco ◽  
Mário S. Dainez-Filho ◽  
Douglas C. Souza ◽  
Sidinei M. Thomaz

2000 ◽  
Vol 26 (4) ◽  
pp. 427-435 ◽  
Author(s):  
Pamela E. Padgett ◽  
Sheila N. Kee ◽  
Edith B. Allen

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