Life‐history variation following habitat degradation associated with differing fine‐scale spatial genetic structure in a rainforest cycad

Abstract

Habitat degradation can result in drastic environmental changes potentially affecting the life-history of populations and aspects of the reproductive biology and the genetic structure within and among populations. Here, we explore how life-history differences between subpopulations from contrasting habitats may affect mating availability, which in turn will indirectly affect the strength of spatial genetic structure within populations of a tropical rainforest cycad (Zamia fairchildiana). Subpopulations exposed to higher light availability in degraded-forest habitats had male individuals that grew faster, reproduced earlier, and invested more in reproduction than in nativeforest habitat subpopulations. These differences in life history resulted in degraded-habitat subpopulations showing a higher proportion of reproductive adults and greater mate availability in a reproductive season. Subpopulations in the degraded habitat showed weaker SGS, i.e., a smaller slope in the linear regression of genetic relatedness on linear distance. Environmentally induced changes in life history and subsequent changes in the strength of the SGS after habitat degradation may have important consequences for population viability and should be of concern in conservation.

Zamia(Cycadales: Zamiaceae) on Puerto Rico: Asymmetric genetic differentiation and the hypothesis of multiple introductions

“…ex A. Dietrich) in secondary forest, which they attributed to higher light levels. Lopez‐Gallego and O'Neil (2009) reported similar findings for Z. fairchildiana L. D. Gómez. If this is a constant component of life history in undisturbed forest populations of Z. erosa , it would further reinforce the gene‐flow constraints engendered by pollination and dispersal biology, discussed previously, as well as facilitate the accumulation of private alleles.…”

“…This study represents the most intensive population genetics investigation of a cycad to date in terms of number of markers, and one of only a few microsatellite studies of plant populations from the Caribbean biodiversity hotspot (Namoff et al, 2011; Calonje et al, 2012; Geiger et al, 2012) or of cycads in general (Meerow et al, 2007, 2012; Lopez‐Gallego and O'Neil, 2009; Cibrián‐Jaramillo et al, 2010).…”

Fine-scale spatial genetic structure of Dalbergia nigra (Fabaceae), a threatened and endemic tree of the Brazilian Atlantic Forest

“…In plants, gene flow through the pollen and seeds determines whether alleles are widely or locally dispersed ( Bradshaw, 1972 ; Levin and Kerster, 1974 ). However, the dispersion distance is small compared to the area covered by plant populations, which can promote fine-scale SGS ( Vekemans and Hardy, 2004 ; Lopez-Gallego and O’Neil, 2010 ). Seed dispersal more strongly influences genetic structuring of populations than pollen movement ( Chung et al , 2003 ).…”

Will the same ex situ protocols give similar results for closely related species?

“…Environmental differences: bay rush occurs in full sun on coastal white limestone sand dunes, whereas sinkhole cycad occurs in deep shade at the bottom of humus-rich sinkholes. These environmental differences can influence gene flow, fecundity, germination, seedling recruitment, and survival (Clark and Clark 1987;Lopez-Gallego and O'Neil 2010) and therefore alter the demographic structure of populations. In addition to these biological and geographic factors, we selected these two species for logistic reasons.…”