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Amphibian Unit 1

What is Batrachology?

the study of amphibians

Why are amphibians and reptiles often studied together?

1. historical inertia
2. tradition

3. many aspects of their lives are complimentary

4. similar modes of investigation

5. biological similarities

Amphibian Skin

moist and scaleless

Amphibian skeleton

ossified but flexible, some have more cartiledge

Amphibian reproduction

internal/external, indirect and direct development

Amphibians are what kind of "therms?"

Poikilotherms - they adjust temp based on external environment

What kind of heart do amphs have?

3-chambered heart

What is heterochrony?

(embryonic) heterochrony refers to alterations in the timing and rate of developmental processes that change the body form of adults

What is ontogeny?

the process of a single cell (egg or zygote) to an adult organism

Which two organisms' larvae resemble their adult stage in appearance and organization?

Salamanders and caecilians

Anurans

frogs/toads

All larval amphibians share what traits?

1. promote aquatic existence (thin, highly vascular skin, gills)
2. lidless eyes and large nonvalvular nares

3. the body is muscular and adapted for undulatory swimming

4. skeleton is mostly cartilaginous

5. well-developed lateral line system

What natural processes affect physiological processes of juveniles and adults, especially embryos?

Temperature, gas exchange, and water availability

Metamorphosis

signals the completion of embryogenesis and is initiated internally by thyroxine - env factors can initiate early release

Only a few amphibians hatch eggs. This process is driven by glands that secrete what

proteolytic enzymes that weaken and dissolve egg capsule

Growth

both indeterminate (attenuated) and determinate (asymptomatic)

Size of an amphibian is determined by

1. genetic potential
2. size at hatching

3. abundance and quality of food during growth

4. sex

How long do amphibians live?

Most less than 7 years, but can live up to 25 years

Amphibian sense organs

1. 10 cranial nerves
2. cutaneous sense organs

--mechanoreceptors (lateral line and tactile)

Amphibian respiratory surfaces

1. skin
2. gills

3. lungs

4. buccopharyngeal (cheek, mouth, pharynx)

Amphibian lifecycle

1. physically tied to water to reproduce
2. mostly internalized fertilization (salamanders)

3. both direct and indirect development *

4. biphasic and biennial ****

1/3 salamander species are found in

North America

The highest concentration of salamanders is found in

the Appalachian Mountains

Amphibian declines due to

1. habitat destruction
2. invasive species

3. pollution

4. unsustainable use (subsistence, commercial exploitation)

5. Disease/parasitism, climate change

Two qualifications to be considered a hotspot region

1. at least 1500 vascular plant species as endemics (naturally occurring)
2. lost at least 70% original habitat

Why are amphibians better bioindicator species?

1. permeable skin
2. found in and around water

3. reproduction is tied to water

4. complex life cycle

5. physiology makes them more sensitive to env changes

Issues in political ecology

1. habitat loss and pollution
2. invasive species

3. global climate change

4. unsustainable use

5. disease

Why are amphibians traded?

1. pet trade
2. skin trade

3. bushmeat

current issues in amphibian ecology

1. political ecology
2. trade in exotic wildlife

3. sport/commercial hunting/fishing

Human effect of habitat modification/fragmentation/loss...

urban sprawl, wetland mitigation banking - wolf in sheep's clothing

Promises v Problems of pesticide use

Promise is quick but dirty fix, economical fix; Problem is development of resistance, secondary pest outbreaks, adverse human and env health problems

Alternative pest control methods

1. cultural control
2. biological control (natural enemies)

3. genetic control

4. chemical ecology (hormones)

5. physical + natural barriers

6. control w sterile males

7. biotechnology (resistant strain of crop/plant)

8. IPM (integrated pest management) - long term management

Direct take v indirect take

Direct take shows intent, indirect take does not show intent

Max sustained yield

a population declines once this value is exceeded

optimum sustained yield

level of sustained yield determined by species interaction, esthetics, and land use problems

Sustainability

process or state that can be maintained indefinitely

what is urban blight

general deterioration of structures and facilities in addition to a decline in quality of services (education, etc)

the lifeboat ethic

the argument to the effect that we should limit amount of food-aid to high-population countries to prevent further population growth

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Däck
Ajami
Oh là là vocabulaire! w5
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