David B. Weissman

Understanding the genetic effects of recent habitat fragmentation in the context of evolutionary history: Phylogeography and landscape genetics of a southern California endemic Jerusalem cricket (Orthoptera: Stenopelmatidae: Stenopelmatus)

Habitat loss and fragmentation due to urbanization are the most pervasive threats to biodiversity in southern California. Loss of habitat and fragmentation can lower migration rates and genetic connectivity among remaining populations of native species, reducing genetic variability and increasing extinction risk. However, it may be difficult to separate the effects of recent anthropogenic fragmentation from the genetic signature of prehistoric fragmentation due to previous natural geological and climatic changes. To address these challenges, we examined the phylogenetic and population genetic structure of a flightless insect endemic to cismontane southern California, Stenopelmatus‘mahogani’ (Orthoptera: Stenopelmatidae). Analyses of mitochondrial DNA sequence data suggest that diversification across southern California began during the Pleistocene, with most haplotypes currently restricted to a single population. Patterns of genetic divergence correlate with contemporary urbanization, even after correcting for (geographical information system) GIS‐based reconstructions of fragmentation during the Pleistocene. Theoretical simulations confirm that contemporary patterns of genetic structure could be produced by recent urban fragmentation using biologically reasonable assumptions about model parameters. Diversity within populations was positively correlated with current fragment size, but not prehistoric fragment size, suggesting that the effects of increased drift following anthropogenic fragmentation are already being seen. Loss of genetic connectivity and diversity can hinder a populations ability to adapt to ecological perturbations commonly associated with urbanization, such as habitat degradation, climatic changes and introduced species. Consequently, our results underscore the importance of preserving and restoring landscape connectivity for long‐term persistence of low vagility native species.

Loss of genetic connectivity and diversity in urban microreserves in a southern California endemic Jerusalem cricket (Orthoptera: Stenopelmatidae: Stenopelmatus n. sp. ''santa monica'')

Microreserves may be useful in protecting native arthropod diversity in urbanized landscapes. However, species that do not disperse through the urban matrix may eventually be lost from these fragments. Population extinctions may be precipitated by an increase in genetic differentiation among fragments and loss of genetic diversity within fragments, and these effects should become stronger with time. We analyzed population genetic structure in the dispersal limited Jerusalem cricket Stenopelmatus n. sp. “santa monica” in the Santa Monica Mountains and Simi Hills north of Los Angeles, California (CA), to determine the impacts of fragmentation over the past 70 years. MtDNA divergence was greater among urban fragments than within contiguous habitat and was positively correlated with fragment age. MtDNA genetic diversity within fragments increased with fragment size and decreased with fragment age. Genetic divergence across 38 anonymous nuclear Inter-Simple Sequence Repeat (ISSR) loci was influenced by the presence of major highways and highway age, but there was no effect of additional urban fragmentation. ISSR diversity was not correlated with fragment size or age. Differing results between markers may be due to male-biased dispersal, or different effective population sizes, sorting rates, or mutation rates among sampled genes. Results suggest that genetic connectivity among populations has been disrupted by highways and urban development, prior to declines in local population sizes. We emphasize that genetic connectivity can rapidly erode in fragmented landscapes and that flightless arthropods can serve as sensitive indicators for these effects.

Zoogeography of the Grasshoppers and Their Relatives (Orthoptera) on the California Channel Islands

Twelve of fifty-four Orthoptera species (22-2 %) found on the eight California Channel Islands off the coast of Southern California are endemic, 11 9% in the northern four-island subgroup and 22 2 % in the southern four-island subgroup. A general analysis of the distribution of these endemics, especially those in the cricket genus Cnemotettix and those endemic species capable of flight, was conducted. The results indicate that autochthonous speciation, and not the occurrence of mainland relicts, explains these high endemic numbers. A regression analysis of log island area versus log number of Orthoptera species yields results similar to those of other plant and animal species. Faunistically rich land masses that lie within 20 km of one Channel Island are disproportionately more important as source areas than those land masses at distances exceeding 20 km. Simple regression of environmental components correlated with faunal diversity shows that for untransformed data, Orthoptera species numbers are significantly explained by area (82 %) and elevation (74 %). For log transformed data, the significance of area in explaining Orthoptera species number is diminished to 5700, while elevation explains 78 %, which is almost unchanged from before transformation. * Present address: David B. Weissman, University of California, Irvine, College of Medicine, Medical Student Affairs, Irvine, California 92717. Introduction Island biogeography, with its conceptual base largely laid by early works of Preston (1962) and MacArthur & Wilson (1963, 1967), is rapidly becoming an explicit, predictive portion of ecological theory. Insights into explanations of species distributions, community structure, and competitive interactions among species on islands come from many sources (see Diamond, 1973; Simberloff, 1974). Several such works (i.e. Diamond, 1969, 1971; Power, 1972; Lynch & Johnson, 1974; Hunt & Hunt, 1974; Johnson, Mason & Raven, 1968; Savage, 1967; von Bloeker, 1967) were specifically conducted on the California Channel Islands (see Fig. 1). These islands are particularly useful for testing many biogeographical tenets because only eight islands are involved: the Channel Islands are closer, fewer, and smaller than other island groups (i.e. Hawaiian, Galapagos, Canary, West Indies, etc.) from which extensive empirical biogeographical data have also come. Additionally, all eight Channel Islands are presently located near the mainland. This permits identification and comparison of island and mainland (source) faunas and assessment of probable speciation patterns. Also, the four northern (San Miguel, Santa Rosa, Santa Cruz, and Anacapa) and four southern (San Nicolas, Santa Catalina, San Clemente, and Santa Barbara) islands are themselves cohesive subgroups with reference to (i) geological similarity (see below) and (ii) gradients of size (and corresponding topographic diversity) and isolation (see Table 2). This paper is the first to present a comprehensive zoogeographical analysis of any insect group (specifically the Orthoptera) found on the Channel Islands. Six years (1969-74) of extensive field work on all the Channel Islands and adjacent mainland areas form the foundation for this analysis. Detailed census methods and complete species list are presented elsewhere (Rentz & Weissman, 1973, 1976).

Functional equivalence of grasping cerci and nuptial food gifts in promoting ejaculate transfer in katydids.

The function of nuptial gifts has generated longstanding debate. Nuptial gifts consumed during ejaculate transfer may allow males to transfer more ejaculate than is optimal for females. However, gifts may simultaneously represent male investment in offspring. Evolutionary loss of nuptial gifts can help elucidate pressures driving their evolution. In most katydids (Orthoptera: Tettigoniidae), males transfer a spermatophore comprising two parts: the ejaculate‐containing ampulla and the spermatophylax—a gelatinous gift that females eat during ejaculate transfer. Many species, however, have reduced or no spermatophylaces and many have prolonged copulation. Across 44 katydid species, we tested whether spermatophylaces and prolonged copulation following spermatophore transfer are alternative adaptations to protect the ejaculate. We also tested whether prolonged copulation was associated with (i) male cercal adaptations, helping prevent female disengagement, and (ii) female resistance behavior. As predicted, prolonged copulation following (but not before) spermatophore transfer was associated with reduced nuptial gifts, differences in the functional morphology of male cerci, and behavioral resistance by females during copulation. Furthermore, longer copulation following spermatophore transfer was associated with larger ejaculates, across species with reduced nuptial gifts. Our results demonstrate that nuptial gifts and the use of grasping cerci to prolong ejaculate transfer are functionally equivalent.

Notes on southern Africa Jerusalem crickets (Orthoptera: Stenopelmatidae: Sia).

The Old World Jerusalem cricket (JC) subfamily Siinae contains one genus, Sia, with two subgenera: Sia (Sia) with two fully winged species from southeast Asia, and Sia (Maxentius) with four wingless species from southern Africa. Because there is a dearth of published data about the behavior and biology of these insects, we present new field and laboratory research on southern African Sia (Maxentius), gather museum and literature information, and present guidelines for collecting and rearing specimens. While we make no taxonomic decisions, this review should be useful for future studies, including a needed taxonomic revision. We also compare results from these southern African JCs with recent investigations on related New World taxa, where fascinating biological traits and extensive cryptic biodiversity have been uncovered. DNA analysis reveals that these Old and New World JCs are polyphyletic.