Transcript BCB 311 Biodiversity & Conservation Biology

Contemporary Amphibians: Are we
changing their environment ?
http://tolweb.org/Living_Amphibians
Angela Campher
Biodiversity & Conservation Biology
University of the Western Cape
Bellville 7535
[email protected]
General Characteristics of Amphibians
 “Amphibians occurs within three groups namely
salamanders and newts: toads and frogs: and
caecilians”-Mader (2004)
 organ level of organization - body cavity
containing organs
 tube-in-tube body plan and have a coelom
General Characteristics of Amphibians
 Have some outstanding feature that was not seen
within other groups of organisms before presence of limbs
 - tongue * use to catch prey
 - eyelids * functions to keep eyes moist
 - ears * able to hear or pick-up sound waves
 - voice * which is produced in the larynx
 Within their life cycle they have both an aquatic
and terrestrial life stage.
General Characteristics of Amphibians
 They undergo metamorphosis - which is the
process by which an organism undergoes a
change in body form.
 Amphibians have smooth, non-scaly, moist skin
which is porous and which contains a mucus layer
 The mucus layer is secreted by mucus glands
within the skin, the skin has various functions
namely
 - water balance, respiration, temperature
regulation
General Characteristics of Amphibians
 Amphibians are ectotherms, this means that they
are dependant upon the environment to regulate
their temperature (body) - Mader (2004)
Characteristics of three groups
 Group 1 - Salamanders and Newts, represent
earliest fossil, they have two pairs of legs-90º
angle to each other
 - dorsi-ventrally flattened body, elongated
 - movement via sinusoidal motion
 - are carnivorous, feeding on invertebrates e.g.
snails
Characteristics of three groups
 Group 2 - Frogs and Toads, have a fused head and
trunk with the absence of a tail
 They have muscle padded hind legs which are
long and powerful for jumping, frogs vary from
toads in that it’s skin is smooth and that they have
long legs.
 Toads on the other hand have warty skin and
snout body's, also preferring a dark and moist
habitat away from water, where as frogs live by or
in fresh water streams or masses.
Characteristics of three groups
 Group 3 - Caecilians, seems to resemble amelids
owing to their long worm-like body forms.
 They reach lengths of 1 metre and have folds on
their skin-thus resembling segments (but it is not)
.
Geographical Distribution
 Their dependence on environmental conditions for
body temperature regulation allow for them to
occur within certain places in the world.
 They are found within various Biogeographical
realms e.g.
 - Australia
 - Afro and Neotropical
 - Oceanic or Nearctic
 - Palearotic and or Indomalayan Realms
Geographical Distribution
 More specifically they are abundant in North and
South America, Africa, Asia, Europe, Middle East,
Australia and Oceania.
 Amphibians do not occur in Greenland or
Antarctica owing to extremely cold condition.
 Their diversities are higher in the tropics.
Supportive Habitats
 Amphibians are highly successful seen that they
have made it possible to occupy various areas or
countries world wide.
 They are directly dependant upon the habitats
these countries provide thus also being able to
occupy various biomes.
 Forests, Savannas, Shrublands, Grasslands,
Aquatic habitats and Deserts are biomes which
they can persist and survive in.
 Within these habitats you will find them readily
under rocks, stones, logs and close to fast flowing
streams.
Supportive Habitats
 The largest amount of amphibians are found within
wetlands or rain forests
 These biomes are being readily changed and the
habitats for frogs are thus being threatened and
this affects the abundance and diversity of
amphibians directly
The Carboniferous Period - Age of Amphibians
 Amphibians existed on earth 300 million years ago
 They first appeared on the earth during the
Devonian Period 360-408 million years ago
 This was because the Devonian Period which was
known as the Age of fishes, allowed for the
amphibian to evolve, owing to the fact that Labefinned fishes are believed to be ancestral to the
amphibians
 The Carboniferous swamp forest was the suitable
habitat for primitive amphibians owing to its high
water, food and trees supply
The Carboniferous Period - Age of Amphibians
 Those favourable resources today have been
threatened over the past few decades and have
thus affected our current Amphibian populations
world wide
 There are 6000sp of known amphibians and their
abundance's are being decreased rapidly over the
past 50 years
Climate Change
 Past climates provided conditions for maximum
vascular plant growth, insect population
flunishment and amphibian expansion in both
diversity and number
 When looking at climatic conditions today, we
have to realize that our climate has undergone
changes over the past few decades
 Proxy data and instrumental measurements of
climatic variables have provided us with
information about climatic conditions over millions
of years ago
Climate Change
 There are various factors responsible for this
change and these changes are affecting
amphibian population abundances world wide
Factors Affecting Amphibian Decline
 There is a link between climate change and
amphibian number decline owing to temperature
precipitation fluctuations
 Climate change is not directly responsible for this
decline but it does affect the organisms variability
to diseases and this will lead to a decrease in
population number or death of species
 Various factors plays a part in amphibian species
decline, it has to be noted that some factors are
more influential than others
Amphibian Decline is owing to the:
 Destruction and alteration of their natural habitats
 introduction of predators into their habitats
 consumption of amphibians by humans e.g. red
legged frog
 pollution of the water and atmosphere
 climate change observed or change in climatic
conditions
 increased level of radiation and
 transformation of landscaped
 draining of wetlands
Amphibian Decline is owing to the:
 spreading of wildlife diseases e.g.
Chytridiomycosis and Ranaviral
 deformation and malformation of species owing to
environmental conditions
Are we changing contemporary amphibians
environment?
 When looking at the list of factors causing a
decrease in amphibians species numbers then it is
evident that most of those factors are due to
human activity
 Therefore yes, we are changing their environment,
we are changing the natural habitats of
amphibians through planting crops-agriculture
and deforestation
 We are either introducing other species into
amphibians habitats which out compete current
amphibians and or feed on them (predation)
Are we changing contemporary amphibians
environment?
 Because of the increase burning of fossil fuels we
are raising the amount of green house gases in the
atmosphere thus causing global warming
 This allows for an increase in local climates, owing
to the pollution of the atmosphere and the
population levels in the water has now become
more concentrated
 Ozone also allows for increased levels of the UV-B
radiation to penetrate the earth’s surface and this
is harmful towards amphibians
Are we changing contemporary amphibians
environment?
 Swing to urbanization landscapes have been
transformed and this caused a change within the
amphibian environment thus affecting their
development directly - wetlands were also drained
for human advantage e.g. stream channelization
 There is therefore a link between climate change
and declines5
The Effects on Biodiversity
 There are 6000 known species of amphibian and
1/3 threatened, this is 32% of the species
consisting of 1856 sp in total
 43% of amphibians 2469 species are decreasing in
population number
 Decreases with in amphibian diversity and number
is seen in cities, country sides, rainforests and
wetlands
 Most species declines are surprisingly seen within
protected parks
The Effects on Biodiversity
 Some species has gone extinct in Australia and
Coasta Rica namely the Gastric breading frog
(1980) and monteverde golden toad as well
 Because of Amphibians dependence on their
environment, owing to juvenile stage being aquatic
and adult stage being terrestrial, their life as a
whole is sustained by the maintenance of their
habitats.
What can we do?
 The rapid decrease in amphibians sp number has
been identified and has been listed as one of the
most severe issue as to date by conservationist.
 Many conservationist have found methods in
which to conserve the amphibian species which
we do still have living today
 One method used is to educate communities
(human) about amphibians and how we are
affecting these populations directly, thus then also
allowing humans to have a direct part in the
conservation of amphibians
What can we do?
 This is done through monitoring of certain areas
and forming artificial natural habitats for
amphibians
 There are numerous Amphibian Conservation
groups globally
 examples are the :
 PARC - Partners in Amphibians and Reptile
Conservation
 ACA - Amphibian Conservation Alliance
 CARCWET - Canadian Amphibian and Reptile
Conservation Network
What can we do?
 There are 1500000 conservation groups world
wide but yet there is still a decline in amphibians
occurring
 This shows us the serenity of this issue
References
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www.frogs.org
www.blueplanetbiomes.org/savanna
www.rodford.educ/
www.parplace.org
www.wokopedia.org
www.animaldiversity.com