Mini Exam 8-12 PDF

Theme 8: ======== 1. **Describe Radford et al.'s rationale, study design and methodology for assessing the relationship between tree cover and incidence of bird species in Victorian box-ironbark habitat.  What data did they collect, how, and why did they choose to do it that way?** Ra...

Theme 8: ======== 1. **Describe Radford et al.'s rationale, study design and methodology for assessing the relationship between tree cover and incidence of bird species in Victorian box-ironbark habitat.  What data did they collect, how, and why did they choose to do it that way?** Radford et al. aimed to assess how tree cover influences the incidence of bird species in Victorian box-ironbark habitats. Their rationale was based on concerns about habitat loss and fragmentation, which has been linked to the decline of bird populations dependent on woodland environments. The team wanted to identify thresholds of tree cover necessary to maintain viable bird populations. The study design included surveying 24 landscapes, each measuring 10x10 km, representing a range of tree cover from 2% to 60%. These landscapes were further categorized based on whether the vegetation was aggregated in large blocks or dispersed across the landscape in smaller patches, strips, and scattered trees. The researchers systematically surveyed birds at 10 sites within each landscape, covering various landscape elements such as small and large patches, roadsides, streamside vegetation, and scattered trees in farmland. They collected data on bird species occurrence (species richness) and incidence, which was measured by how often each species was detected during multiple surveys. The focus was on woodland-dependent birds, which are known to be more sensitive to changes in habitat structure. The study design was chosen to understand the effects of landscape-scale habitat changes on bird populations. By using a range of landscapes with varying levels of vegetation cover, the researchers could analyze how different configurations of tree cover influenced bird incidence and population stability. This method allowed them to explore not only the amount of habitat but also how its arrangement affected bird species. 2. **What did Radford et al.'s study reveal about incidences of different bird species and their overall ecological community in relation to tree cover in woodlands?  What conservation management recommendations were supported by the research? (10 mins)** Findings on Bird Species Incidence and Ecological Communities: - Linear Response: Species like the Little Lorikeet exhibited a steady decline in population size as tree cover decreased. - Curvilinear Response: Species such as the Grey Shrike-thrush showed a more dramatic decline in fragmented habitats due to **isolation effects.** - Step-threshold Response: Species like the Yellow-tufted Honeyeater were only present in landscapes with more than 20% tree cover, indicating they require larger, continuous blocks of habitat. **Conservation Management Recommendations:** - Aim for at least 30-35% Native Vegetation Cover: This level of tree cover was found to support resilient bird populations and maintain ecological processes. Maintaining and restoring landscapes to this level would help protect woodland-dependent species. - Protect Large Habitat Blocks: Large, contiguous blocks of vegetation were essential for area-sensitive species. Protecting these areas from further fragmentation is critical to preserving species diversity. - Promote Connectivity: Maintaining corridors and stepping stones of vegetation between fragmented patches helps mitigate isolation effects and allows species to move across the landscape. - Restoration of Low-Cover Landscapes: For landscapes with less than 10% cover, restoration efforts should focus on increasing vegetation cover and connecting remnant patches to support declining bird species. Theme 9: ======== 1. Define Biocapacity and Ecological Footprint as formulated by the Global Footprint Network.  These two metrics, for a defined geographical region, are measured in Global Hectares.  Explain how a Global Hectare relates to a standard Hectare (a standard Hectare is a fixed unit of area).  When Biocapacity is less than Ecological Footprint for a region, the region is said to be in Ecological Deficit.  What does an Ecological Deficit imply about the ecological sustainability of the region?  (10 mins). The Global Footprint Network defines biocapacity as the ability of ecosystems to produce biological materials useful to humans, regenerate the resources consumed by humans and absorb the generated waste, **especially carbon dioxide emissions**. This is only for human needs, not sustaining life. It is measured in terms of global hectares (gha), which represents the productivity of biologically productive land or sea areas (not and actual hectare). It assumes current management schemes and extraction technologies, it changes from year ti year due to climate, management, and what is consider useful inputs to the human economy. The higher the biological productivity of the land (such as cropland), the more global hectares it equates to. Biocapacity accounts help assess the regenerative capability of a region's ecosystems compared to human demand on those ecosystems​ Ecological Footprint, on the other hand, is a measure of the demand humans place on Earth\'s ecosystems. It calculates the biologically productive area required to supply the resources a population consumes and to absorb its wastes, especially carbon emissions. Like biocapacity, it is measured in global hectares. Suppose the **Ecological Footprint of a region exceeds its Biocapacity. In that case, the region is in what is known as Ecological Deficit**, meaning it is using more resources than its ecosystems can regenerate​. Because trade is global, an individual or country´s footprint includes land or sea from all over the world. A global hectare is a unit of measurement that **adjusts a standard hectare** (which is simply 10,000 square meters or about 2.47 acres) by **accounting for the average biological productivity of the land** (**yield**). Since different types of land (e.g., forests, croplands, grazing lands) have varying productivity levels, the global hectare allows for comparisons across these different land types. For example, a hectare of fertile cropland may represent more global hectares than a less productive hectare of pastureland​. When a region experiences an **Ecological Deficit, it implies that the region\'s consumption is unsustainable, relationship between consumption and production is unsustainabke**. It is using resources faster than the ecosystem can regenerate them, which may result in resource depletion, increased carbon emissions, and environmental degradation because we are using resources without replacement (running down ecological capital hence reducing biocapacity). Such a deficit means the region relies on external sources for resources or overexploits its own natural assets, reducing its long-term ecological resilience, impact on non-human forms, and sustainability​. In summary, a balance between Ecological Footprint and Biocapacity is critical for sustainability. When Biocapacity is less than the Ecological Footprint, it indicates a situation of overconsumption and environmental stress, which poses risks to future resource availability. Theme 10 ======== Outline the range of questions in conservation biology that can be addressed using molecular markers.  Illustrate your answer with reference to real examples.  1. **Species Identification and Hybridization** - **Problem**: Determining the species of an individual or detecting hybridization between species is crucial for protecting biodiversity. - **Example**: Mitochondrial DNA (mtDNA) and nuclear markers like microsatellites are commonly used for species identification and detecting hybridization. The **Baker et al. study** used nuclear DNA markers to identify individual whale species, detecting illegal use of whales in commercial products​(Theme 10 - 2-page PDF). - **Application**: Molecular markers help distinguish closely related species and uncover hybrid individuals that might complicate conservation efforts. This is especially important in areas with hybrid zones where species interbreed. 2. **Population Structure and Connectivity** - **Problem**: Understanding how populations are structured and how connected they are across landscapes is essential for managing wildlife and planning conservation strategies. - **Example**: Assignment tests, as illustrated in **Sam Wasser\'s elephant poaching investigation**, used genetic profiles to track the geographic origins of poached ivory, pinpointing concentrated poaching locations in Africa​(Theme 10 - 2-page PDF). - **Application**: These markers reveal the movement patterns of species, showing how fragmented landscapes affect population connectivity, critical for species survival in fragmented habitats. 3. **Genetic Diversity and Inbreeding** - **Problem**: Loss of genetic diversity reduces a population\'s ability to adapt to changing environments, leading to inbreeding depression. - **Example**: The **genetic rescue of the Eastern barred bandicoots (EBBs)**, discussed by Andrew Weeks and Ary Hoffmann, used molecular markers to assess genetic diversity and inbreeding. After introducing new genetic material, the fitness of the population was expected to increase​(Theme 10 - 2-page PDF). - **Application**: Genetic markers assess the level of genetic variation within populations and help detect inbreeding, which informs decisions on translocation and captive breeding programs aimed at increasing genetic diversity. 4. **Monitoring and Estimating Population Sizes** - **Problem**: Accurately estimating population sizes, particularly for elusive or endangered species, is challenging with traditional survey methods. - **Example**: Non-invasive genetic sampling techniques, such as using **scats or hair** collected in the field, are analyzed with molecular markers to estimate population sizes without disturbing the animals​(Theme 10 - 2-page PDF). - **Application**: DNA from non-invasive samples helps to estimate population sizes and track individuals over time, which is critical for monitoring the success of conservation efforts. 5. **Tracking Illegal Wildlife Trade** - **Problem**: The illegal wildlife trade poses a significant threat to many species, and identifying the origin of confiscated animal parts is key to enforcement. - **Example**: In the **Witness for the Whales project**, genetic markers were used to track whale products and identify species involved in illegal whaling operations​(Theme 10 - 2-page PDF). - **Application**: Molecular markers allow conservationists and law enforcement to track and identify the species and population of origin for illegally traded wildlife products, aiding in crime prevention and species protection. 6. **Understanding Evolutionary Adaptation and Fitness** - **Problem**: Conservation efforts often need to understand how populations adapt to environmental changes such as climate change or habitat loss. - **Example**: SNPs (single nucleotide polymorphisms), which are increasingly replacing microsatellites, are used to detect adaptive differences between populations, such as those observed in populations undergoing **genetic rescue**​(Theme 10 - 2-page PDF). - **Application**: By examining genetic markers under selection, conservationists can determine how populations might evolve in response to changing environments, guiding strategies that promote evolutionary resilience. ### Conclusion: Molecular markers offer a powerful means to address a diverse range of questions in conservation biology, from species identification to tracking genetic diversity and managing population connectivity. These markers not only provide insights into the genetic health of populations but also offer practical applications for wildlife conservation, such as monitoring illegal trade and designing effective management strategies. Theme 11: ========= **How are the impacts of genetic drift and selection on genetic variation in populations controlled by effective population size?  (10 mins)** Effective population size (Ne) plays a crucial role in determining the relative impacts of genetic drift and selection on genetic variation in populations. Genetic Drift: Genetic drift refers to random changes in allele frequencies due to chance events. Its effect is stronger in smaller populations because random fluctuations are more likely to significantly impact the genetic makeup of a small group. In populations with a small Ne, genetic drift can lead to the loss of genetic variation more quickly, causing certain alleles to become fixed (reach 100% frequency) or lost entirely. Over time, this reduces genetic diversity. Selection: Natural selection, on the other hand, acts on specific alleles based on their effects on fitness (i.e., survival and reproduction). In larger populations (with a larger Ne), selection can effectively act on beneficial alleles, increasing their frequency, while deleterious alleles are purged more efficiently. However, in small populations, the effects of genetic drift can overpower selection, making it harder for natural selection to fix beneficial alleles or remove deleterious ones, which could lead to maladaptive changes in the population. Effective Population Size (Ne) controls the balance between these forces: - Small Ne: Drift dominates. The effects of chance are strong, leading to greater loss of genetic variation, and potentially less efficient selection. - Large Ne: Selection becomes more powerful in determining allele frequencies, and drift has a smaller effect. Genetic variation is maintained more effectively, and adaptive alleles can spread more readily through the population. In summary, a larger Ne reduces the impact of genetic drift and enhances the efficacy of selection in shaping genetic variation, while a smaller Ne increases the impact of drift and can limit the influence of selection.