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Costa Rica Field Course - Coggle Diagram

- - - - Over 30 Hypotheses exist
        
        3 main ones
        
        Time for Speciation Hypothesis
        
        Focus on the role of climatic history enabling lower latitude regions to accumulate greater biodiversity
        
        Areas of higher latitudes have been subject to repeated glaciations and periods of significant drying or cooling
        
        More frequent extinctions as a result
        
        Lower Latitudes have maintained a relatively constant warm and humid climate for tens of millions of years
        
        More time for species to evolve, diversify and accumulate
        
        Diversification Rate Hypothesis
        
        Faster diversification rates closer to the equator drive the LDG
        
        Net accumulation of species over time (i.e. rate of speciation - the rate of extinction)
        
        Overlaps with the time for speciation hypothesis
        
        Lower extinction rates due to a more stable climate would increase the diversification rate
        
        Diversification rate can rise with an increased rate of speciation
        
        most of the proposed mechanisms for latitudinal variation in diversification focus on this
        
        E.g. Evolutionary Speed Hypothesis
        
        2 more items...
        
        Productivity Hypothesis
        
        The rate at which an ecosystem generates new organic matter
        
        Energy availability within a food web constrains diversity within an ecosystem
        
        Greater water and solar availability closer to the equator = greater plant diversity and productivity
        
        More abundant plant material + greater diversity of food sources and habitats = greater diversity for herbivores, predators and parasites
        
        The metabolic rate of a plant is constrained by the intensity and duration of sunlight and moisture
        
        Faster rates of biotic interactions and coevolutionary processes (mutation, selection, gene flow)
        
        Likely a combination of several
        
        Time theory
        
        For millions of years, tropical regions have remained relatively stable in terms of climate
        
        Unlike temperate areas which experienced repeated glaciation during the ice ages
        
        This has allowed species to evolve, diversify and persist without regular disruption
        
        Specialisation/ Competition Hypothesis
        
        Many species have evolved to occupy very specific niches
        
        Rapoport's rule
        
        species ranges are lower in the tropics and increase with latitude
    - - Null model used to determine the cause of the LDG as it doesn't assume a biological driver
      - Aims to use geographical constraints to predict species richness in areas where boundaries limit the ranges of species
      - E.g. species richness is predicted to be highest at mid-elevation
  - - - More opportunity for species interactions such as pollination, seed dispersal and competition = drivers of evolutionary change over time
    - - Canopy, understory, forest floor. etc
      - Variations in altitude, soil type and rainfall across the landscape = patchwork of microhabitats
        
        More niches and increased opportunity for diversification
- - - - Relocating to cooler environments (higher altitudes, shifting towards the poles, descending into deeper ocean zones)
      - Essential for avoiding extinction and maintaining survival
  - - - movement is impossible (e.g. summit-restricted species can no longer move upwards)
  - - - Correlative models
        
        Use statistical relationships between species and their environments
      - Mechanistic models
        
        Species' physiology and behaviour (e.g. thermal tolerance, metabolic rate. etc)
        
        More recent and realistic
    - - Species can't move without restriction and barriers such as urban-development or fragmented landscapes limit species' movement
    - - reveals that apparently suitable habitats often remain empty because essential partners are absent or competitors exclude colonists
  - - - Could lead to maladaptive behaviours, reduced fitness, and population declines
  - - - Increased focus on landscape connectivity such as wildlife corridors
  - - - Biodiversity is increasingly shaped by mobile, generalist species, while specialists decline
- - - - Disease
        
        Chytrid Fungus
        
        Major cause of decline in 500+ species
        
        Spreading faster now due to rising temeratures
      - Habitat Loss/ exploitation
        
        Affects 93% of threatened amphibian species
        
        Anthropogenic (Construction and urban development, deforestation and agriculture) or natural (natural disasters, wildfitres. etc)
        
        Salamanders = most at risk group of amphibians in terms of habitat toss
      - Climate Change
        
        Extreme temperatures, extreme weather, increased intensity and frequency of tropical storms, increased ground UV radiation due to diminishing ozone layer
        
        Habitat destruction, altered breeding cycles, maladaptive behaviour, mismatched ecosystems and food webs, reproductive failure, increased spread of disease
        
        Climate linked epidemic hypothesis
        
        increased cloud cover and global warming can provide optimal conditions to facilitate pathogen growth and fungal spread
      - Engimatic declines
        
        Unknown/ no specific cause
        
        could be a combination of factors or a new, currently unknown factor
- - - - E.g. 'Approach and Avoid' management (animals are moved towards or away from stimuli through understanding what attracts or deters them). Scientists use this to manipulate environments to produce desired responses
        
        Encouraging animals toward higher-quality habitats, increasing the use of conservation corridors, helping them avoid invasive predators or reducing collisions with vehicles
        
        Outperforms traditional methods that may otherwise cause unintended outcomes like ecological traps (where animals are attracted to environments that seem suitable but are actually detrimental to their survival)
      - E.g Placing conspecific carcasses supporting conservation efforts
      - E.g Habituation and sensitisation for more peaceful coexistence with humans (good for ecotourism. etc)
- - - - Normally a deterrent backed up by a species
    - - Over time, predators learn to avoid conspicuous prey via exposure
  - - - Breaks down body outlines and is very effective against complex backgrounds
    - - Organisms portray similar colours to their habitat/ darker on top and lighter on the bottom to remove shadow presence
    - - Animals impersonate static objects like sticks or leaves
  - - - Palatable prey species evolving warning colours to impersonate harmful, non-palatable species
      - Aims to protect an individual by deceiving predators
        
        Works well in small numbers and is reliant on an abundance of other edible prey
        
        Whole system may collapse if their are too many cheaters as predators learn to disassociate the particular colouration with danger
        
        This is known as negative frequency dependent selection
      - Coommon in insect species
    - - Species that have a secondary defence ro are generally distasteful all portraying similar warning colours and patterns in order to benefit all species and increase the mutual protection of all involved
      - Decreases the learning time of predators due to increased rate of encounters, eventually lowering the threat of being harmed over time
      - This type of mimicry informs the predator rather than deceiving it
- - - - Alleviates poverty-driven deforestation by providing financial compensation to landowners in exchange for forest conservation
        
        It's effectiveness in addressing poverty remains limited (low payment amounts and restricted access for small-scale farmers reduce participation as payments often fail to outweigh the economic benefits of more exploitative land uses
  - - - NGOs are working to mitigate this conflict through improved livestock management, predator deterrents, and community outreach programmes
    - - Conservation strategies must be tailored to local customs, values, and attitudes towards wildlife
  - - - Association of Artisanal Fishing Folk of the South Caribbean Coast launched an initiative focusing on public awareness and combining periodic removals with annual tournaments to control lionfish consumption
  - - - Effects on marine ecosystems remains poorly understood but we do know that idling boats produce higher local concentrations of pollutants due to reduced propeller dispersal
        
        conservation strategies include mandating four-stroke engines which release fewer pollutants and, potentially, installing docking bays to reduce engine idling
      - A form of tourism designed to engage visitors with local communities and natural environments while minimising ecological impacts
    - - Increased urban development nearby
        
        Increased habitat fragmentation and ecological isolation
        
        Increased isolation and reduced genetic diversity
      - Affects animal behaviour
      - Trail erosion, wildlife disturbance and waste accumulation
  - - - Costa Rica is one of the world's largest users of pesticides
      - interrupts life cycles of invertebrates, kills off plants
        
        Affects at the bottom of the food chain have knock-on effects further up the food chain
      - Heavy rainfall in the tropics worsens this situations due to runoff
      - Biorefineries help reduce the reliance on fossil fuels, minimise landfill use and reduce methane emissions
- - - - E.g. Overfishing or deforestation or fragmentation. etc
    - - E.g. insecticides
- - - - These 11 conservation areas cover over 25% of national territory
    - - Incorporates a range of sectors, such as agriculture and economics, to ensure adequate finding is balanced between projects