Effects of habitat fragmentation on population structure and fitness components of the wetland specialist Swertia perennis L. (Gentianaceae)

Lienert, Judit; Diemer, Matthias; Schmid, Bernhard

doi:10.1078/1439-1791-00089

Cited by 55 publications

(56 citation statements)

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“…Most of the local extinctions could be attributed to habitat fragmentation and some to changed land use as well (Lienert, Fischer, and Diemer, 2002). Moreover, we found that habitat fragmentation significantly reduced plant density and fitness (Lienert, Diemer, and Schmid, 2002) and that S. perennis is highly susceptible to inbreeding depression (J. Lienert and M. Fischer, unpublished data).…”

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confidence: 87%

“…We assessed the genetic structure of 17 populations of S. perennis in northeastern Switzerland with isozyme electrophoresis. Moreover, we tested whether measures of isozyme variability were correlated with fitness measures and with the magnitude of herbivory recorded in an earlier study (Lienert, Diemer, and Schmid, 2002). We asked the following questions: (1) How large is the isozyme variability of S. perennis?…”

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Isozyme variability of the wetland specialistSwertia perennis(Gentianaceae) in relation to habitat size, isolation, and plant fitness

Lienert

Fischer

Schneller

et al. 2002

American J of Botany

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We examined the effects of size and spatial isolation of fens on the isozyme variability of 17 populations of Swertia perennis. This long-lived perennial is a locally abundant fen specialist in Switzerland, where wetlands have been strongly fragmented. Isozyme variability was comparable to other outcrossing plants (A ϭ 1.53, AP p ϭ 2.01, P p ϭ 42.5, H o ϭ 0.113, H e ϭ 0.139). F statistics indicated both inbreeding within and differentiation between populations (F IS ϭ 0.076, F IT ϭ 0.194, F ST ϭ 0.128), with moderate gene flow between populations (N e m ϭ 1.703). Populations in small, isolated fens had reduced genetic variability and the highest withinpopulation inbreeding coefficients (F IS ). Isozyme variability was significantly associated with vegetative fitness traits (MANOVA), and the magnitude of leaf herbivory decreased as the percentage of polymorphic loci increased. These data suggest that the reduced genetic variability of S. perennis in small, isolated populations may reduce plant fitness, thereby increasing susceptibility to herbivore damage. Our study also shows that habitat fragmentation can reduce the genetic variability of populations of fairly common habitat specialists, which so far have attracted less conservation attention than rare species.

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confidence: 99%

Isozyme variability of the wetland specialistSwertia perennis(Gentianaceae) in relation to habitat size, isolation, and plant fitness

Lienert

Fischer

Schneller

et al. 2002

American J of Botany

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“…These possible dangers for small populations motivated recent studies that explored the effect of population size and/or genetic diversity on plant performance measured as seed production, seed germination or plant growth (e.g. SCHMIDT & JENSEN 2000, MUSTAJARVI et al 2001, LIENERT et al 2002, PASCHKE et al 2002, OOSTERMEIJER et al 2003. Most of these studies indicate poorer performance of individuals in small populations.…”

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Effect of population size on the prospect of species survival

Münzbergová

2006

Folia Geobot

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Abstract:Many recent studies have demonstrated a negative effect of small population size on single plant traits. However, not much is known about the actual consequences of reduced plant performance on the long-term prospect of species survival.I studied the effect of population size on population growth rate and survival probability in the rare perennial herb Scorzonera hispanica occurring in fragmented grasslands. Its performance was measured using several traits related to reproduction in 21 populations ranging in size from 3 to 2475 plants. These data were then connected with data on full demography of the species from three of the studied populations. Two different matrix models differing in the number of transitions based on measurements in the populations differing in size were used to explore the relationship between population size and population growth rate.Both matrix models showed that despite the decline in seed production in small populations, population growth rate is never significantly different from one, and the populations could thus be expected to survive in the long run. Calculations of extinction probabilities that take into account demographic and environmental stochasticity, however, showed that populations below 100 flowering individuals have a high probability to become extinct. This demonstrates that demographic and environmental stochasticity is an important driver of the fate of small populations in this system. This study demonstrates that estimation of population growth rate can provide new insights into the effect of population size on population growth and survival. It also shows how matrix models enable the combination various pieces of information about the single populations into one overall measure, and may provide a useful tool for the standardization of studies on the effects of population size on population performance.

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“…Negative effects of inbreeding on individual performance have been documented for instance for reproductive traits and offspring establishment (Fishman, 2001;Lienert, Diemer, & Schmid, 2002;Pflugshaupt, Kollmann, Fischer, & Roy, 2002;Paschke, Abs, & Schmid, 2002b;Lienert & Fischer, 2004) and in various groups of organisms and environments (Armbruster, Hutchinson, & Linvell, 2000;Andersson & Waldmann, 2002;Haag, Hottinger, Riek, & Ebert 2002;Keller & Waller, 2002). These effects may be due to recessive alleles that are deleterious when homozygous (partial dominance hypothesis), an advantage in fitness of heterozygotes compared to homozygotes (overdominance hypothesis ;Charlesworth & Charlesworth, 1987), or an increase in developmental instability in homozygotes (but see Clark, 1993).…”

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confidence: 99%

Effects of inbreeding and pollen donor provenance and diversity on offspring performance under environmental stress in the rare plant Cochlearia bavarica

Paschke

Bernasconi

Schmid

2005

Basic and Applied Ecology

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SummaryHabitat degradation and loss can reduce size and genetic variability of natural populations, increasing individual homozygosity and average relatedness between individuals. While the resulting inbreeding depression may be reduced by natural selection under prevailing environmental conditions, it may increase again under environmental stress. To investigate the effect of environmental stress on offspring performance and the expression of inbreeding depression, we hand-pollinated maternal plants in small (o 100, n ¼ 5) and large populations (4 400 flowering plants, n ¼ 5) of the rare plant Cochlearia bavarica (Brassicaceae) and raised the offspring under experimentally manipulated water and light regimes (normal or reduced supply). In addition to considering natural variation in inbreeding levels due to population size, we manipulated pollen donor provenance and diversity. Maternal plants were pollinated with nine donors from a different population or with one or nine donors from the same population. One further inflorescence of each maternal plant was exposed to free pollination. Offspring growth and survival were monitored over 300 days. Offspring performance varied significantly among populations and maternal plants. Environmental stress interacted significantly with these factors. However, there was no general indication that offspring from small populations were more negatively affected. In seven out of 10 populations, offspring derived from between-population pollination performed better than offspring derived from withinpopulation pollination. Also, in five out of 10 populations, average offspring size was KEYWORDS Environmental stress; Genetic variation; Inbreeding depression; Outbreeding; Pollen diversity; Population size; Rare plant species; Reaction norm higher after within-population pollination with nine than after pollination with one pollen donor. These results suggest low genetic diversity within C. bavarica populations, both smaller and larger ones. Interactions between environmental stress and pollination treatment indicated that using pollen donors from outside a population or increasing the number of pollen donors can reduce inbreeding depression, but that this beneficial effect is impaired under stressful conditions.

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Effects of habitat fragmentation on population structure and fitness components of the wetland specialist Swertia perennis L. (Gentianaceae)

Cited by 55 publications

References 36 publications

Isozyme variability of the wetland specialistSwertia perennis(Gentianaceae) in relation to habitat size, isolation, and plant fitness

Isozyme variability of the wetland specialistSwertia perennis(Gentianaceae) in relation to habitat size, isolation, and plant fitness

Effect of population size on the prospect of species survival

Effects of inbreeding and pollen donor provenance and diversity on offspring performance under environmental stress in the rare plant Cochlearia bavarica

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