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Immigration rates and species niche characteristics affect the relationship between species richness and habitat heterogeneity in modeled meta-communities.

Bar-Massada A - PeerJ (2015)

Bottom Line: Increased environmental heterogeneity will decrease effective habitat sizes, which in turn will increase the rate of local species extinctions.I found that both positive and unimodal richness-heterogeneity relationships can occur in meta-communities in patchy landscapes.Meta-communities comprising generalist species are therefore likely to exhibit unimodal richness-heterogeneity relationships as long as low immigration rates prevent rescue effects and patches are small.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biology and Environment, University of Haifa , Kiryat Tivon , Israel.

ABSTRACT
The positive relationship between habitat heterogeneity and species richness is a cornerstone of ecology. Recently, it was suggested that this relationship should be unimodal rather than linear due to a tradeoff between environmental heterogeneity and population sizes. Increased environmental heterogeneity will decrease effective habitat sizes, which in turn will increase the rate of local species extinctions. The occurrence of the unimodal richness-heterogeneity relationship at the habitat scale was confirmed in both empirical and theoretical studies. However, it is unclear whether it can occur at broader spatial scales, for meta-communities in diverse and patchy landscapes. Here, I used a spatially explicit meta-community model to quantify the roles of two species-level characteristics, niche width and immigration rates, on the type of the richness-heterogeneity relationship at the landscape scale. I found that both positive and unimodal richness-heterogeneity relationships can occur in meta-communities in patchy landscapes. The type of the relationship was affected by the interactions between inter-patch immigration rates and species' niche widths. Unimodal relationships were prominent in meta-communities comprising species with wide niches but low inter-patch immigration rates. In contrast, meta-communities consisting of species with narrow niches and high immigration rates exhibited positive relationships. Meta-communities comprising generalist species are therefore likely to exhibit unimodal richness-heterogeneity relationships as long as low immigration rates prevent rescue effects and patches are small. The richness-heterogeneity relationship at the landscape scale is dictated by species' niche widths and inter-patch immigration rates. These immigration rates, in turn, depend on the interaction between species dispersal capabilities and habitat connectivity, highlighting the roles of both species traits and landscape structure in generating the richness-heterogeneity relationship at the landscape scale.

No MeSH data available.


Effect of inter-patch distance on the probability of propagule arrival into a patch.Each curve is based on a different z parameter (Eq. (5)).
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fig-1: Effect of inter-patch distance on the probability of propagule arrival into a patch.Each curve is based on a different z parameter (Eq. (5)).

Mentions: During model simulations, I pre-determined niche width and immigration rates (z in Eq. (5)) to assess their effects on the relationship between meta-community species richness and landscape scale environmental heterogeneity. I tested all possible combinations of σ = 1, 5, 10, and 50 (from very narrow to wide niches, respectively). To alter immigration rates, I ran the simulations with four different values of z: 0.2, 0.1, 0.05, and 0.025, which correspond with increasing rates of inter-patch immigration, respectively (Fig. 1).


Immigration rates and species niche characteristics affect the relationship between species richness and habitat heterogeneity in modeled meta-communities.

Bar-Massada A - PeerJ (2015)

Effect of inter-patch distance on the probability of propagule arrival into a patch.Each curve is based on a different z parameter (Eq. (5)).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4359120&req=5

fig-1: Effect of inter-patch distance on the probability of propagule arrival into a patch.Each curve is based on a different z parameter (Eq. (5)).
Mentions: During model simulations, I pre-determined niche width and immigration rates (z in Eq. (5)) to assess their effects on the relationship between meta-community species richness and landscape scale environmental heterogeneity. I tested all possible combinations of σ = 1, 5, 10, and 50 (from very narrow to wide niches, respectively). To alter immigration rates, I ran the simulations with four different values of z: 0.2, 0.1, 0.05, and 0.025, which correspond with increasing rates of inter-patch immigration, respectively (Fig. 1).

Bottom Line: Increased environmental heterogeneity will decrease effective habitat sizes, which in turn will increase the rate of local species extinctions.I found that both positive and unimodal richness-heterogeneity relationships can occur in meta-communities in patchy landscapes.Meta-communities comprising generalist species are therefore likely to exhibit unimodal richness-heterogeneity relationships as long as low immigration rates prevent rescue effects and patches are small.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biology and Environment, University of Haifa , Kiryat Tivon , Israel.

ABSTRACT
The positive relationship between habitat heterogeneity and species richness is a cornerstone of ecology. Recently, it was suggested that this relationship should be unimodal rather than linear due to a tradeoff between environmental heterogeneity and population sizes. Increased environmental heterogeneity will decrease effective habitat sizes, which in turn will increase the rate of local species extinctions. The occurrence of the unimodal richness-heterogeneity relationship at the habitat scale was confirmed in both empirical and theoretical studies. However, it is unclear whether it can occur at broader spatial scales, for meta-communities in diverse and patchy landscapes. Here, I used a spatially explicit meta-community model to quantify the roles of two species-level characteristics, niche width and immigration rates, on the type of the richness-heterogeneity relationship at the landscape scale. I found that both positive and unimodal richness-heterogeneity relationships can occur in meta-communities in patchy landscapes. The type of the relationship was affected by the interactions between inter-patch immigration rates and species' niche widths. Unimodal relationships were prominent in meta-communities comprising species with wide niches but low inter-patch immigration rates. In contrast, meta-communities consisting of species with narrow niches and high immigration rates exhibited positive relationships. Meta-communities comprising generalist species are therefore likely to exhibit unimodal richness-heterogeneity relationships as long as low immigration rates prevent rescue effects and patches are small. The richness-heterogeneity relationship at the landscape scale is dictated by species' niche widths and inter-patch immigration rates. These immigration rates, in turn, depend on the interaction between species dispersal capabilities and habitat connectivity, highlighting the roles of both species traits and landscape structure in generating the richness-heterogeneity relationship at the landscape scale.

No MeSH data available.