Elizabeth E. Crone, Atticus W. Murphy, Cheryl B. Schultz
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引用次数: 0
Abstract
Decisions about which processes to include in a population model can have substantial impact on estimates of population trends and extinction risk. This is particularly important for species of conservation concern, whose conservation status is decided in part on the basis of these models.In their recent paper, Meehan and Crossley (2023) Insect Conservation and Diversity, 16, 566–573 revisit a time series of overwintering monarch butterfly abundances, which previous assessments had characterised as rapidly declining and at risk of extinction. The authors, in contrast, reported no evidence for declines in the past 10 years and characterised extinction risk as low.A primary reason for the difference between these conclusions was that Meehan and Crossley used a more complex model that included a parameter for density dependence. While negative density dependence may play a role in monarch population regulation, there are a variety of unresolved issues with how and if density dependence should be included in models of monarch populations, including widely known issues with separating observation error from density dependence in noisy time series and taxon‐specific issues with fitting models to data surveyed every fourth generation and pooled at continental scales.These issues make the conclusions of Meehan and Crossley about monarch population viability much less robust than implied in their article. They do not provide convincing evidence that density dependence reduces extinction risk in monarch butterflies. Our commentary supports their general conclusion that population viability projections depend on model assumptions, but the ways in which monarch butterfly populations are regulated remains an open question.
期刊介绍:
To publish papers of the highest scientific quality within the general area of insect (and other arthropods) conservation and diversity covering topics ranging from ecological theory to practical management.
Papers are invited on the following topics: Conservation genetics; Extinction debt; Long-term conservation planning and implementation; Global implications of local or national conservation actions; Management responses of species and communities; Captive breeding programs; Comparisons of restored and natural habitats; Biogeography; Global biodiversity; Metapopulation dynamics; Climate change: impacts on distributions and range; Invasive species: impacts and control; Effects of pollution; Genetic threats to diversity by introgression; Effects of fragmentation on diversity and distribution; Impact of agricultural and forestry practices on biodiversity; Enhancing urban environments for diversity and protection; Biodiversity action plans: can we scale up from insects?; Effectiveness and choice of indicator species; Soil biodiversity and interactions with above-ground biodiversity; Ecological interactions at local levels; Ecological and evolutionary factors influencing diversity and local, regional and global scales; Sustainable livelihoods and training on the ground; Integrating science and policy.