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Abstract Hybridization is a common process that has broadly impacted the evolution of multicellular eukaryotes; however, how ecological factors influence this process remains poorly understood. Here, we report the findings of a 3-year recapture study of the Bryant’s woodrat (Neotoma bryanti) and desert woodrat (Neotoma lepida), two species that hybridize within a creosote bush (Larrea tridentata) shrubland in Whitewater, CA, USA. We used a genotype-by-sequencing approach to characterize the ancestry distribution of individuals across this hybrid zone coupled with Cormack–Jolly–Seber modeling to describe demography. We identified a high frequency of hybridization at this site with ~40% of individuals possessing admixed ancestry, which is the result of multigenerational backcrossing and advanced hybrid-hybrid crossing. F1, F2, and advanced generation hybrids had apparent survival rates similar to parental N. bryanti, while parental and backcross N. lepida had lower apparent survival rates and were far less abundant. Compared to bimodal hybrid zones where hybrids are often rare and selected against, we find that hybrids at Whitewater are common and have comparable survival to the dominant parental species, N. bryanti. The frequency of hybridization at Whitewater is therefore likely limited by the abundance of the less common parental species, N. lepida, rather than selection against hybrids.
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Demographic responses of hybridizing cinquefoils to changing climate in the Colorado Rocky Mountains
Abstract Hybridization between taxa generates new pools of genetic variation that can lead to different environmental responses and demographic trajectories over time than seen in parental lineages. The potential for hybrids to have novel environmental tolerances may be increasingly important in mountainous regions, which are rapidly warming and drying due to climate change. Demographic analysis makes it possible to quantify within‐ and among‐species responses to variation in climate and to predict population growth rates as those conditions change. We estimated vital rates and population growth in 13 natural populations of two cinquefoil taxa (Potentilla hippianaandP. pulcherrima) and their hybrid across elevation gradients in the Southern Rockies. Using three consecutive years of environmental and demographic data, we compared the demographic responses of hybrid and parental taxa to environmental variation across space and time. All three taxa had lower predicted population growth rates under warm, dry conditions. However, the magnitude of these responses varied among taxa and populations. Hybrids had consistently lower predicted population growth rates thanP. hippiana. In contrast, hybrid performance relative toP. pulcherrimavaried with population and climate, with the hybrid maintaining relatively stable growth rates while populations ofP. pulcherrimashrank under warm, dry conditions. Our findings demonstrate that hybrids in this system are neither intrinsically unfit nor universally more vigorous than parents, suggesting that the demographic consequences of hybridization are context‐dependent. Our results also imply that shifts to warmer and drier conditions could have particularly negative repercussions forP. pulcherrima, which is currently the most abundant taxon in the study area, possibly as a legacy of more favorable historical climates. More broadly, the distributions of these long‐lived taxa are lagging behind their demographic trajectories, such that the currently less commonP. hippianacould become the most abundant of thePotentillataxa as this region continues to warm and dry.
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- PAR ID:
- 10470633
- Publisher / Repository:
- John Wiley & Sons Ltd
- Date Published:
- Journal Name:
- Ecology and Evolution
- Volume:
- 13
- Issue:
- 7
- ISSN:
- 2045-7758
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Delmore, Kira (Ed.)Abstract Hybridization produces a range of outcomes from advantageous to disadvantageous, and a goal of genetic research is to understand the gene interactions that generate these outcomes. Interactions between cytoplasmic elements, such as mitochondria, and the nucleus may be particularly vulnerable to accruing disadvantageous combinations as a result of their different rates of evolution. Consequently, mitonuclear incompatibilities may play an important role in hybrid outcomes even if their negative impacts could be masked for some fitness measures by heterosis in first-generation (F1) hybrids. We used Tigriopus californicus, a model system for mitonuclear incompatibilities that is also known for exhibiting heterosis in the F1 generation and outbreeding depression in later generations, to test whether heterosis or outbreeding depression would occur when mitonuclear mismatch was paired with a stress that heavily impacts mitochondrial processes—specifically, hypoxia. We generated 284 parental and 436 F1 hybrids from four population crosses (720 total) and compared parental and F1 populations for hypoxia tolerance. We observed that, on average, F1 hybrids were less likely to survive a hypoxia stress test than parental populations, although we did not detect a statistically significant trend (P = 0.246 to 0.614). This suggests that hypoxia may be a particularly intense stressor for mitonuclear coordination and hybridization outcomes vary by trait.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1002/ece3.10097
