1. Population Size:
* Minimum Viable Population (MVP): The smallest number of individuals needed for a population to have a reasonable chance of surviving for a specified time period (usually hundreds of years). This is influenced by factors like breeding rate, mortality rate, and genetic diversity.
* Effective Population Size (Ne): This considers the number of individuals actually contributing to the next generation, factoring in genetic variation and breeding success. A smaller Ne indicates less genetic diversity and a higher risk of extinction.
2. Genetic Diversity:
* High Genetic Diversity: A diverse gene pool allows populations to adapt to changing environments, resist diseases, and avoid inbreeding depression.
* Low Genetic Diversity: Inbreeding can lead to weaker offspring, reduced disease resistance, and lower overall fitness, increasing the risk of extinction.
3. Habitat Quality and Availability:
* Adequate Habitat: A population needs sufficient space, resources (food, water, shelter), and suitable environmental conditions to thrive.
* Habitat Fragmentation: When habitats are divided, populations can become isolated, leading to smaller, more vulnerable groups.
4. Demographic Factors:
* Age Structure: A balanced age distribution (with enough young and mature individuals) ensures continued reproduction and population growth.
* Sex Ratio: A balanced sex ratio is necessary for successful reproduction.
5. Environmental Factors:
* Climate Change: Changing climate patterns can impact habitat availability, food resources, and disease dynamics, affecting population viability.
* Natural Disasters: Fires, floods, and other natural events can decimate populations.
6. Human Impacts:
* Habitat Destruction: Human activities like deforestation, urbanization, and agriculture can significantly reduce habitat availability.
* Overexploitation: Excessive hunting, fishing, or harvesting can push populations towards extinction.
* Pollution: Pollution can contaminate habitats, food sources, and water, harming populations.
7. Connectivity:
* Gene Flow: Migration between populations allows for gene exchange, maintaining genetic diversity and resilience.
* Barriers to Migration: Obstacles to movement like roads, fences, or fragmented habitats can isolate populations and decrease their long-term viability.
In summary, a viable animal population is one that has a large enough size, diverse genetic makeup, access to adequate habitat, balanced age structure, and a healthy environment with minimal human impacts. These factors are interconnected and work together to ensure the long-term survival of a species.