Population Resiliency Needs – Summary In general, we depict population resiliency for Darlost’s Island mouse below, in Figure 7: Resiliency for Darlost’s Island mouse requires healthy populations across the range of ecological settings on the Island, including the Coastal Plains, Paradise Palms, and Mountain habitats; healthy populations are sufficiently large (>= 100 individuals), have a positive growth rate (including adequate adult, juvenile survival rates and adequate fecundity), and sufficient immigration occurs to ensure connectivity between populations such that genetic diversity is ensured. Additionally, beetle abundance is sufficient and sufficient quantity of high quality habitat that provide food resources and cover, including beachgrass, friable soil, and interstitial spaces, that are free of, or have manageable, threats. Current uncertainties and unknowns that we have include: MVP >= 1: While there is generalized information from one well studied population (The Beach Bums) and Cave Petroglyph data (see Caves on Interactive Map), Misty Mountain’s Population of 50 individuals brings this MVP number into question. Further research would be needed to see if the Misty Mountain is exhibiting any deleterious effects (genetic drift for example) from their smaller population size. However, the resiliency of a population of 100 is much greater than that for a population of 50, especially given the types of stochastic events on the island. A sufficient population growth rate is unknown. A sufficient adult mouse survival rate is unknown. The juvenile survival rate is unknown. The sex ratio needed for sufficient reproductive success is assumed to be 1:1 due to both parents caring for young, but this has not been documented in the literature. The quantity of habitat area is unknown (what is the necessary “patch” size?) Carrying capacity – we are do not know what habitat area is needed for what population size. Quality of habitat needed – though we know that beach grass, friable soils, interstial spaces of sufficient quality are needed, we are unable to define the quality of these habitats more specifically, beyond the generalities of present ambient temperatures (80-100 degrees, current amount of precipitation, etc.). Area of occupation for populations is currently unknown. Connectivity requirements (amount of genetic exchange) – Movement between populations is essential for genetic health via gene flow and we know that genetic exchange currently occurs between various populations via sparrows, migration, emigration, and perhaps other mechanisms, but the amount of exchange necessary is unknown.
Scenario 1 (IPCC Likelihood:______Unlikely_______________________) Population name Population Factors Habitat Factors (overall) abundance Population growth Genetic Diversity beetle abundance Beach grass Cover Future condition Beach Bums HIGH MOD HIGH MOD HIGH MOD HIGH Message in a Bottle HIGH MOD LOW HIGH HIGH HIGH HIGH Cannibal Cove HIGH HIGH LOW HIGH HIGH HIGH HIGH Castaways LOW LOW LOW LOW LOW LOW LOW Snowmelt Thicket MOD MOD LOW HIGH HIGH HIGH MOD Deadman’s Dunes LOW LOW HIGH HIGH HIGH MOD MOD Treasure Grove MOD MOD HIGH MOD MOD MOD MOD of Spirits MOD MOD HIGH MOD MOD MOD MOD Misty Mountain LOW LOW MOD LOW MOD LOW LOW Darlost’s Dome LOW MOD LOW MOD MOD HIGH MOD Skull Mountain X X X X X X extirpated Scenario 2 (IPCC Likelihood:_____About as likely as not________________) Population name Population Factors Habitat Factors (overall) abundance Population growth Genetic Diversity beetle abundance Beach grass Cover Future condition Beach Bums HIGH MOD HIGH MOD HIGH MOD HIGH Message in a Bottle MOD MOD LOW MOD MOD MOD MOD Cannibal Cove MOD LOW LOW HIGH HIGH HIGH MOD Castaways LOW LOW LOW LOW LOW LOW LOW Snowmelt Thicket MOD MOD LOW HIGH HIGH HIGH MOD Deadman’s Dunes LOW LOW HIGH MOD MOD LOW LOW Treasure Grove LOW LOW HIGH MOD MOD MOD LOW Realm of Spirits MOD LOW HIGH MOD MOD MOD MOD Misty Mountain LOW LOW MOD LOW MOD MOD LOW Darlost’s Dome LOW MOD LOW MOD MOD HIGH MOD
Snowmelt Thicket MOD MOD MOD LOW Deadman’s MOD MOD LOW LOW Treasure Grove MOD MOD LOW LOW Realm of Spirits MOD MOD MOD LOW PARADISE PALMS ECOLOGICAL SETTING MOD MOD LOW LOW Misty Mountain MOD LOW LOW LOW Darlost’s Dome MOD MOD LOW LOW Mountain X X X X MOUNTAIN ECOLOGICAL SETTING MOD MOD LOW LOW Characterize species’ Resiliency, Redundancy and Representation For each Scenario, populations were mapped and tallied by level of resilience (high, moderate, low) for each Ecological Setting. Table 9 Future Redundancy Scenario Coastal Paradise Mountains High Mod Low High Mod Low High Mod Low 1 3 0 1 0 4 0 0 1 1 2 1 2 1 0 2 2 0 0 2 3 0 1 3 0 0 4 0 0 2 below is a mapping of the populations (and their resiliency level) for Scenario 2 GREEN = HIGH ORANGE = MOD RED = LOW COASTAL PARADISE PALMS MOUNTAIN 1. Beach Bums 5. Snowmelt Thicket 9. Mountain 2. Message in a Bottle 6. Deadman’s Dunes 10. Darlost’s Dome 3. Cannibal Cove 7. Treasure Grove 11. Mountain (extirpated) 4. Castaways 8. Realm of Spirits