Cannibalism and density-dependent mortality in the wolf spider Pardosa milvina (Araneae: Lycosidae)

2003 ◽  
Vol 81 (8) ◽  
pp. 1293-1297 ◽  
Author(s):  
Christopher M Buddle ◽  
Sean E Walker ◽  
Ann L Rypstra
Keyword(s):  
Population Regulation ◽  
Wolf Spider ◽  
Field Studies ◽  
Agricultural Fields ◽  
Eastern North America ◽  
Wolf Spiders ◽  
Conspecific Density ◽  
Pardosa Milvina ◽  
Density Dependent Mortality ◽  
Dependent Mortality

Cannibalism is an important regulating mechanism in many terrestrial and aquatic arthropod communities. Spider ecologists have suggested that cannibalism with wolf spiders (Araneae: Lycosidae) in the genera Schizocosa and Pardosa is common and can act in population regulation. This hypothesis was tested with the species Pardosa milvina (Hentz), a small wolf spider that shows high densities in disturbance-driven ecosystems, including agricultural fields, throughout eastern North America. Under laboratory conditions, cannibalism was more common between pairs of P. milvina with the greatest differences in both mass and size. Field studies, in which we stocked natural densities, 2× natural densities, and 4× natural densities of P. milvina in enclosures placed in soybean fields, revealed that survival was lowest when conspecific density was highest, and larger individuals prevailed under high-density conditions. Thus, cannibalism likely plays an important role in governing populations of P. milvina, and the generality about the prevalence and importance of cannibalism with wolf spiders is supported.

Mortality patterns for a population of burrowing wolf spiders, Geolycosa domifex (Hancock), living in southern Ontario

1983 ◽  
Vol 61 (12) ◽  
pp. 2758-2767 ◽  
Author(s):  
D. J. McQueen
Keyword(s):  
Life History ◽  
Life Span ◽  
Additional Data ◽  
Field Site ◽  
Maximum Life Span ◽  
Wolf Spiders ◽  
Southern Ontario ◽  
Density Dependent ◽  
Density Dependent Mortality ◽  
Dependent Mortality

A population of burrowing wolf spiders, Geolycosa domifex (Hancock), was studied near Toronto, Ontario, between 1974 and 1979. Some preliminary life history and mortality information for this population has been published previously by D. J. McQueen. In the paper that follows, these results are updated and additional data pertaining to density-dependent mortality and the effects of the parasite Pterodontia flavipes Grey are presented. At the Uxbridge field site, the maximum life span for G. domifex was 3 years and they were semelparous. On average, the wasp Anoplius relativus (Fox) killed 18.7% of the population at age 24 months and >98% of the female spiders after they had reproduced at age 36 months. The acrocerid fly, P. flavipes killed 40.4% of the population at age 22 months and an average of 17.5% of the population at age 34 months (before reproduction). Younger spiders were not killed by either A. relativus or P. flavipes. An analysis of survivorship with respect to burrow spacing suggested that there was no density-dependent mortality.

scholarly journals Density-dependent adult recruitment in a low-density tropical tree

2018 ◽  
Vol 115 (44) ◽  
pp. 11268-11273 ◽  
Author(s):  
James R. Kellner ◽  
Stephen P. Hubbell
Keyword(s):  
Tree Species ◽  
Adult Population ◽  
Adult Density ◽  
Tree Recruitment ◽  
Density Dependent ◽  
Conspecific Density ◽  
Density Dependent Mortality ◽  
Conspecific Adult ◽  
Adult Tree ◽  
Dependent Mortality

The Janzen–Connell hypothesis is a well-known explanation for why tropical forests have large numbers of tree species. A fundamental prediction of the hypothesis is that the probability of adult recruitment is less in regions of high conspecific adult density, a pattern mediated by density-dependent mortality in juvenile life stages. Although there is strong evidence in many tree species that seeds, seedlings, and saplings suffer conspecific density-dependent mortality, no study has shown that adult tree recruitment is negatively density dependent. Density-dependent adult recruitment is necessary for the Janzen–Connell mechanism to regulate tree populations. Here, we report density-dependent adult recruitment in the population of Handroanthus guayacan, a wind-dispersed Neotropical canopy tree species. We use data from high-resolution remote sensing to track individual trees with proven capacity to flower in a lowland moist forest landscape in Panama and analyze these data in a Bayesian framework similar to capture–recapture analysis. We independently quantify probabilities of adult tree recruitment and detection and show that adult recruitment is negatively density dependent. The annualized probability of adult recruitment was 3.03% ⋅ year−1. Despite the detection of negative density dependence in adult recruitment, it was insufficient to stabilize the adult population of H. guayacan, which increased significantly in size over the decade of observation.

Field studies of growth, reproduction, and mortality in the burrowing wolf spider Geolycosa domifex (Hancock)

1978 ◽  
Vol 56 (9) ◽  
pp. 2037-2049 ◽  
Author(s):  
Donald J. McQueen
Keyword(s):  
Life History ◽  
Gene Flow ◽  
Wolf Spider ◽  
Field Studies ◽  
Wolf Spiders ◽  
Original Cohort ◽  
The Third ◽  
History Of

A population of burrowing wolf spiders (Geolycosa domifex (Hancock)) was studied near Toronto, Canada, from 1974 to 1977. By following the life history of individuals in marked burrows, it was found that females produce one brood when they are 3 years old. Juveniles leave their mothers during July and August, after which they search for suitable burrow sites, establish burrows, and overwinter. During this period approximately 85% of the juveniles die and the average burrow diameter increases from 1 mm in August to 2–3 mm in October. In the second summer approximately 9% of the original cohort die and the average burrow diameter is 7 mm when the remaining individuals overwinter. In the third summer 4–5% of the original cohort die and burrow diameters average 13 mm when the remaining individuals overwinter. In the fourth summer the remaining 1 or 2% of the original cohort reproduce and more than 99% of these are killed by acrocerid flies (Pterodontia flavipes Grey) and pompilid wasps (Anoplius relativus (Fox)). Because < 0.008% of the original cohort survive to reproduce in their 4th year of life, three separate cohorts occupy the same habitat with little (< 1%) gene flow between them.

scholarly journals THE EFFECTS OF MOISTURE AND HEAT ON THE EFFICACY OF CHEMICAL CUES USED IN PREDATOR DETECTION BY THE WOLF SPIDER PARDOSA MILVINA (ARANEAE, LYCOSIDAE)

2005 ◽  
Vol 33 (3) ◽  
pp. 857-861 ◽  
Author(s):  
Shawn M. Wilder ◽  
Jill DeVito ◽  
Matthew H. Persons ◽  
Ann L. Rypstra
Keyword(s):  
Chemical Cues ◽  
Wolf Spider ◽  
Predator Detection ◽  
Pardosa Milvina

Life history of tundra-dwelling wolf spiders (Araneae: Lycosidae) from the Yukon Territory, Canada

2012 ◽  
Vol 90 (6) ◽  
pp. 714-721 ◽  
Author(s):  
J.J. Bowden ◽  
C.M. Buddle
Keyword(s):  
Reproductive Effort ◽  
Abiotic Factors ◽  
Wolf Spider ◽  
Local Variation ◽  
Yukon Territory ◽  
The Arctic ◽  
Wolf Spiders ◽  
Female Body Size ◽  
Trade Offs ◽  
History Of

We studied populations of three tundra-dwelling wolf spider (Lycosidae) species to determine reproductive trait relationships and developmental timing in the Arctic. We collected 451 Pardosa lapponica (Thorell, 1872), 176 Pardosa sodalis Holm, 1970, and 117 Pardosa moesta Banks, 1892 during summer 2008. We used log-likelihood ratio tests and multiple linear regressions to determine the best predictors of fecundity and relative reproductive effort. Female body size best explained the variation in fecundity and body condition was the best predictor for relative reproductive effort. We tested for a trade-off between the allocation of resources to individual eggs and the number of eggs produced (fecundity) within each species using linear regression. There was variation in detectable egg size and number trade-offs among sites and these may be related to local variation in resource allocation linked to density-related biotic or abiotic factors. These findings contribute to knowledge about the fitness of arctic wolf spiders in the region of study and are particularly relevant in light of the effects that climate changes are predicted to have on the arctic fauna.

Reproductive isolation and sex-role reversal in two sympatric sand-dwelling wolf spiders of the genus Allocosa

2008 ◽  
Vol 86 (7) ◽  
pp. 648-658 ◽  
Author(s):  
A. Aisenberg ◽  
F. G. Costa
Keyword(s):  
Reproductive Isolation ◽  
Sexual Size Dimorphism ◽  
Sex Role ◽  
Wolf Spider ◽  
Coastal Dunes ◽  
Pitfall Trap ◽  
Role Reversal ◽  
Adult Size ◽  
Wolf Spiders ◽  
Size Dimorphism

Allocosa brasiliensis (Petrunkevitch, 1910) is a nocturnal wolf spider inhabitant of coastal dunes. Pitfall-trap data suggested the occurrence of two sympatric and synchronic morphs, with differences in adult size and abdominal design (minor and major morphs). Previous studies performed with the major morph of A. brasiliensis, postulated courtship-role and sexual size dimorphism reversal for this spider. In the present study, we compare data on development and morphology and test reproductive isolation between morphs of A. brasiliensis, with the hypotheses that the two morphs are reproductively isolated and both show courtship-role reversal. As had been reported for the major morph of A. brasiliensis, the minor-morph females approached the burrows of minor-morph males, entered, initiated courtship, and after copulation, males closed their burrows with female cooperation from the inside. Females did not court or copulate with males belonging to the other morph and, in two cases, major-morph females cannibalised minor-morph males. Morphometrical and developmental data showed differences between morphs. The occurrence of copulation only between individuals of the same morph confirm reproductive isolation, supporting the occurrence of two species. Morphological and behavioural data are consistent with courtship-role-reversal hypotheses for the minor morph, constituting the second report in spiders of this atypical behaviour.

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