LEC145

simplest measure of biodiversity

species richness

~ how many animal/plant species

12 million

how many genetically distinct prokaryotes in a handful of soil

10000+ species

how many global fungi species estimated?

1.5 million

most diverse group of land plants

flowering plants - angiosperms

gradient of species richness worldwide:

number of species of most groups is lowest in poles and increases towards tropics

3 egs. of reverse latitudinal patterns

seabirds, lichens & microbes

seabird greatest abundance is at ..

high latitudes - 17 species in antarctic, 22 in subarctic

maximal lichen diversity is in..

dry/cold regions and boreal forest

4 hypotheses for why there are many more species in tropics than in poles

geographic area, energy-species, rapoports rule & evolutionary speed

geographic area hypothesis

larger area = more species - general positive relationship between land area and number of species that can live on it

energy species hypothesis

availability of resources and climate dictates number of coexisting species

PET

potential evapotranspiration - sum of evaporation and plant transpiration from earth's land and ocean surface to atmosphere

productivity hypothesis

availability of resource dictates number of coexisting species in given area

ambient energy hypothesis

availability of high temperature and water dictates number of coexisting species in a given area

where is temperature a limiting factor

only in the north

rapoport's rule

as latitude decreases towards tropics, decrease in geographical extent of animal and plant species can be observed

taxa in low latitudes

narrow range and environmental tolerance, many species which have narrow niches - niche packing

taxa in high latitudes

wide range and environmental tolerance, few species with wide niches

3 explanations for rapoports rule

climatic variability, glaciation, competition between species

climatic variability

greater at higher latitudes, require broad niche to survive in the north

glaciation

species with high dispersal ability repopulate north, have large geographical range

niches in tropics

high competition with restricted habitat - small niches so more highly evolved with fine adaptations

niches in poles

less competition, limited by environmental factors, broad niches

evolutionary speed in tropics

tropics have had long term stability and faster evolutionary rates

3 traits characterise species-rich tropics

long evolutionary history - more generations. relatively stable existence - lack of glaciation & constantly warm temperatures

alpha diversity

species richness and endemism (species richness of species particular to one location)

beta diversity

species composition & changes in composition between different communities

phylogenetic diversity

based on phylogenetic distance - higher diversity when species in the community are less genetically related

ecosystem function

includes stocks of materials and rates of processes involving energy/matter fluxes between trophic levels and the environment

ecosystem services

benefits provided by ecosystems that contribute to making human life possible and enjoyable

biodiversity hotspot

refers to geographical area that has high species richness

complementarity approach

conserving as much biodiversity as possible in a limited area of land available for conservation

classification criteria for habitats in need of conservation

reduction in quantity - area/distribution, restricted geographical distribution, reduction in a/biotic quality, quantitative analysis of probability of collapse

conservation priority habitats in england

coastal sand dunes, limestone pavements, deciduous woodlands

local/alpha diversity

number of species in a defined area

competitive exclusion

most competitve species drive others to extinction

equilibrium theories say that ..

community diversity is regulated by processes of competition and evolution, to attain steady and stable state

equilibrium theories - 3

niche concept, heterogeneity, island biogeography

non-equilibrium theories say that ..

community diversity is due to processes that prevent equilibrium being reached - interfere with competitive exclusion

non-equilibrium theories - 2

diversity-productivity relationship, disturbance

niche concept

specialisation enables more species to coexist in a given area- tight niche packing - resource specialisation/broad niches - resource overlaps

heterogeneity

more diverse habitats have more niches eg. vertical structure of trees

problems with heterogeneity

mainly zoological as plants have the same basic needs, resources and conditions are not partitioned into discrete packages/niches, doesn't account for most diversity

central paradigm of island biogeography

discrete, numerous communities, capture species that readily disperse and colonise, natural laboratories

species diversity formula =

f (island area + isolation)

how is species diversity balanced

between forces of immigration and extinction, immigration decreases with time, extinction increases with number of species present

why do forces of extinction decline with size

greater abundance resources & greater habitat heterogeneity

how does isolation influence immigration

forces of immigration are greater on near islands, speciation more important on remote islands

4 non-equilibrium explanations for diversity

fluctuating environments, species richness related to productivity, intermediate disturbance hypothesis, dynamic equilibrium model

how is species richness related to productivity

peak diversity at intermediate productivity, declining diversity due to competitive exclusion

intermediate disturbance hypothesis

low disturbance = competitive exclusion. intermediate disturbance = max diversity due to prevention of competitive exclusion. high disturbance = low diversity as few species survive

dynamic equilibrium model

highest diversity under conditions where neither disturbance or competitive exclusion dominate

turnover

species change over time

primary succession

from sterile beginnings - volcanoes, glaciers

secondary succession

on previously colonised land following a major disturbance

autogenic process

species change due to organisms activities - biotic

allogenic process

species change due to external non-biological factors - abiotic eg. climate change

features of early successional species (colonisers/r-selected)

small, fast growing, often no dormancy, often N fixers, more energy for reproduction than biomass

features of late successional species (competitors/k-selected)

large, slow growing, large seeds, animal dispersal, competitive, more energy for biomass than reproduction

colonisation and competition of r-selected

high colonisation ability, low competition ability

colonisation and competition of k-selected

low colonisation ability, high competitive ability

pioneer communities

microbes - bacteria, archaea, fungi. algae, lichens, liverworts, bryophytes

seres

successional stages with characteristic vegetation types and associated biota

how do pioneer species colonise land

light seeds, wind dispersal and high seed production

species replacement - inhibition model

early arrivals competitively inhibit - spread rapidly and monopolise resources

species replacement - facilitation model

succession is a series of sequential invasions, each depends on biological improvement of site by earlier colonist - species die out as changes suit later colonists better

what are the main features of conservation now and historically?

historically - very utilitarian conservation ethic

now - resource use in sustainable ways

prioritises human developmentand biodiversity protection simultaneously.

what are the main features of preservation now and historically?

historically - linked to transcendental movement

now - attempt to maintain remaining areas untouched by humans

hands off approach, focus on intrinsic values of natureand ecosystems without direct human intervention.

4 types of value that species can provide

intrinsic/non use

instrumental

ecological

uniquenesscultural

intrinsic values

cultural

recreational

spiritual

ecosystem services

instrumental values

utilitarian uses

practical uses

food, medicine, ecotourism

bioprospectors - possible new productsfrom nature and ecosystem functions.

ecological values

each species has an ecological value to the other species in the ecosystem

species diversity increases ecosystem stability and ability to adapt

uniqueness values

unique sites have a complementary species composition

what does valuing ecosystem goods and services involve?

supporting nutrient cycling, soil formation and primary production

provisioning water, food, wood, fuel

regulating climate, flood, disease, water purificationand supporting habitats for species.

success of conservation depends on …

money and species value the effectiveness of management and stakeholder engagement. habi

habitat based conservation

protects habitat in every biome and ecosystem, protects as much habitat as possibleand focuses on maintaining ecological processes that support biodiversity and ecosystem functions.

farmland habitat conservation eg. hay meadow conservation

supports thousands of insects and bird species which have been declining for 5 years

approach is to postpone mowing until after breeding

current range of named bird species

10906 - 11189

global trends in biodiversity loss

terrestrial diversity is declining rapidly, conservation efforts have had little effectas human activities and habitat destruction continue to pose significant threats.

main drivers of direct biodiversity loss

habitat loss/fragmentation

overexploitation

invasive species

pollution

climate change

indirect drivers of biodiversity loss

economic factors

cultural factors

policy

demographic factors

consequences of timber extraction/conversion in madagascar

9.1% species driven to extinction by deforestation

43% of their endemic dung beetles are effectively extinct

pollution definition

the introduction of contaminants to the environment that disturb physical and biological systems to

toxic pollution

normally lethal

affects organism function

may persist and bioaccumulate

non-toxic pollution

disturbs behaviour

can be lethal

effect of toxic air pollution in newcastle

eliminated many lichen species due to high SO2 concentration

causes of toxic water pollution

regularly discharged by factories or sewage treatment plans

sediments, fertilisers, pesticides from agriculture

surges because of accidents

effects of toxic water pollution in the rhine

high pollution levels led to the loss of most of its freshwater invertebrate fauna

effect of toxic DDT on raptors

british raptors declined after widespread DDT use

eggs with high DDT levels have thinner shells

bioaccumulation of DDT pesticide is toxic for many nontarget species, passes through trophic levels to predators

effect of non-toxic light pollution

affects behaviour of nocturnal mammals e. sea turtles

effects of noise pollution on birds

affects abundance and species richness of some birds

2 species responses to climate change

species change their phenology

species change their distribution

how can species change their phenology

change life cycle events related to climate variations - insects fly early, birds migrate early

how do species change their distribution

geographic and altitudinal limited by temperature

expansions polewards and uphill, contractions at warm limits and downhill

3 types of species that are less likely to adapt

polar/high elevation species (already at max thermal tolerance)

tropical mountain species (have narrow thermal tolerances)

low motility species

4 underlying causes of biodiversity loss

economic

cultural

policy/institutional

demographic

synergistic effects def

impact of 2 factors is greater than the sum of individual effects

effect of climate change on habitat specialists

climate improves but there isn’t habitat available, species isn’t able to respond to climate change

effect of climate change on habitat generalists

climate improves and habitat is available so species can respond to climate change