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SW Western Australia
Biodiversity in SW Western Australia + Species Response
| Question | Answer |
|---|---|
| Some facts about human impact | Human action has altered >2/3 of the environment 12 million hectares of land was cleared in Australia between 2000-2024 Less than 3% of vertebrates on earth are wild animals (most are domestic animals and humans) |
| Impact of higher temperatures on humans in WA | Less rainfall = more desal plants (uses large amounts of energy and resources) More air-conditioning - $30 million in annual electricity bills |
| Atmospheric CO2 | Already at levels last seen 4 million years ago (Pliocene Epoch), heading towards levels last seen 50 million years ago (Eocene) |
| After Gondwana | After Gondwana, Australia was the only continent to remain fully isolated (no transmigration). It is the oldest, flattest and driest continent (OCBIL) |
| Why is SW WA so biodiverse? | There was aridification since the mid Miocene (23 mya), then major arid/mesic cycles through the Pleistocene (2.8 mya). This "see-saw" over time, along with the lack of mass extinctions led to diversification. |
| Then what? | About 0.5 mya the climate became drier and base flora stabilised -> complex vegetation accumulated over long geological time, resulting in high biodiversity and high endemism |
| Mediterranean Climates | are the most at risk from climate change, and older ecosystems have more specialised ecological reactions (difficult to reinstate and find it harder to adapt) |
| Key Aspects of SW WA (8) | - ancient soils - low rainfall - industrial agriculture - high fragmentation - poor dispersal - aggressive invasives - old lineages + high endemism - high levels of ecological novelty |
| What are predicted effects of CC in SW? | Less rainfall, more drought, increased frequency of heatwaves leads to habitat loss and increased stress on species and ecosystems, landscape is also highly fragmented |
| Dispersal ability | critical for species to change location when under pressure, effects survival in face of climate change |
| Climate change causes shifts for species and ecosystems in... | ranges, timing of biological activity, growth rates, relative abundance, species interactions, cycling of water + nutrients, risk of disturbances (biotic + abiotic) |
| Who is most affected by range shifts? | species that can't move fast enough and/or that depend on conditions that are becoming more rare/highly specialised niches |
| What to do when met with changing conditions (3) | 1. adapt to new conditions 2. shrink in geographic space and hope to maintain populations 3. shift in geographic space (usually polewards or inland towards cooler, wetter climates) |
| Phenology Definition | seasonal timing of plant and animal activities -> CC causes changes in phenology such as lower fitness and mismatched timings (e.g. migratory birds arrive too early/late) |
| Dispersal ability and phenologic changes | Ability relies on ability to move, behaviour, connectivity in landscapes and physical/biotic barriers How to change: phenotypic plasticity (acclimation) or evolutionary change (permanent genotype change) |
| Phenology mismatches | lead to trophic decoupling of the food webs e.g. food available too late/early or not enough (highly impacts off-spring) |
| What traits make a mismatch likely? | - migratory/hibernation patterns - forage availability affected by temperature - income breeder - forage specialist - limited mobility - no alternative food - short life-cycle of forage item |
| Mismatch Types | compensated (mismatch then enhanced match) magnified (mismatch in multiple seasons, then enhanced match in multiple) |
| What makes species more vulnerable to extinction? | exposure, sensitivity and adaptive ability spatial - narrow range, poor dispersers, migratory population - small, decreasing, low density genetic - low variability human interaction |
| Genetic Data in Europe | The LGM (ice-sheets + permafrost) had a big impact on species distributions. major refugia in the south shown by genetic signatures, high diversity and differentiation). Backed up by tracing of following migration routes out of refugia and suture zones |
| Genetic Data in Australia | some similar response but only is areas with high topography, tight ecological gradients and glaciation INSTEAD no glaciation, but major changes in environmental conditions over long timeframes |
| Changes in climate flow | changes in climate -> changes in distributions and interactions -> changes in genetic diversity and structure -> adaptation or extinction |
| Phylogeographic Patterns in Australia | early Pleistocene -> major contractions of biota due to aridity and the formation of sandy deserts multiple localised refugia, persistence of biota through arid cycles |
| Major Refugia | ranges, coastal areas, granite outcrops, areas of species richness and endemism |
| How genetic data can help future predictions | can identify genetic variation for adaptation and assess adaptive capacities |
| What genetic data implies about future biotic response | large scale range expansion through migration has not been the previous response in Australia, so is unlikely to be the future response. However there is evidence for major refugia in ranges and coastal areas. Therefore persistence > migration |
| Persistence of biota through future CC requires: | maintenance of dynamic evolutionary processes mosaic of habitats in heterogenous landscapes conservation of genetic variability and adaptive potential |
Created by:
mishm
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