Assessing changes in functional connectivity in a desert bighorn sheep metapopulation after two generations

Area of Science:

• Conservation biology
• Landscape genetics
• Wildlife ecology

Background:

• Estimating species functional connectivity across fragmented landscapes often uses single time periods, neglecting temporal variation.
• Human-made barriers significantly impact species movement, dispersal, and gene flow, posing challenges for conservation.
• Understanding dynamic metapopulation structure is key to effective wildlife management.

Purpose of the Study:

• To investigate changes in desert bighorn sheep metapopulation structure and gene flow across an interstate highway over time.
• To test the hypothesis that altered interactions with a human-made barrier influenced genetic connectivity.
• To assess the impact of shifts in metapopulation structure on genetic diversity and connectivity.

Main Methods:

• Contrasted genetic structure and gene flow using genotypes from two distinct periods (2000-2003 and 2013-2015).
• Employed population assignment tests, genetic structure analysis, and genetic recapture methods.
• Analyzed changes in movement patterns, distribution, and genetic diversity.

Main Results:

• Desert bighorn sheep crossed an interstate highway between 2013-2015, significantly reducing genetic structure between two populations.
• This contrasts with findings from 2000-2003, where highway crossings were rare or unknown.
• A recently expanded population created new links, decreasing genetic structure among multiple populations, with only slight increases in genetic diversity.

Conclusions:

• Observed significant changes in both structural and functional connectivity of desert bighorn sheep metapopulations over two generations.
• Species movement patterns require periodic reassessment, especially in dynamic and fragmented environments.
• Informed management strategies depend on understanding temporal variations in species interactions with landscape features.