OriGin And Exintiction In PHANEROZOIC EON

By: VARUN DURGE Roll No:33

Outline I. Geological time scaleII. Jack SepkoskiIII.Rates of origination and extinctionIV.Generalist species and specialist

speciesV. Imp terms : Degree of ecological

specialization Population dynamics Geographic range

Geological Time Scale

BIG BANG

HADEAN ARCHEON PROTEROZOIC PHANEROZOIC

PALEOZOIC MESOZOIC CENOZOIC

CAMBRIAN

ORDOVICIAN

TRIASSIC

JURASSIC

CRETACEOUS

10-20 billion

Jack sepkoskicompiled

dataon the

stratigraphic ranges

What did he exactly do? He studied over 4000marine

skeletonized families

.20000Genera

So,what did he conclude?

Rates of Origination And Extinction

TRIASSICORIGINATION

RESULTS

DIVERSITY

MESOZOIC&

CENOZOIC

✘ The rates of origination was highest in recorded animal evolution in

CAMBRIAN ORDOVICIAN

Generalist species Specialist species

Can survive on wide variety of resources. Can tolerate harsh conditions of environments. Most of them are Omnivores

Can thrive only in narrow range of environment. which subsists almost entirely on eucalyptus leaves. Mostly these are Herbivores

1)Degree of ecological specialization: Ecologically specialized species are likely to be more vulnerable than generalized species to changes in their environment. They may also be more likely to speciate because of their more patchy distribution, and newly formed species may be more likely to persist by specializing on different resources and thus avoiding competition with other species.

A)Population Dynamics:Species with low or fluctuating population sizes are especially susceptible to extinction. Some authors believe that speciation is also enhanced by small or fluctuating population sizes, although this hypothesis is controversial..

3)Geographic Range:1)Species with broad geographic ranges tend to have a lower risk of extinction because they are not extinguished by local enviromental changes. They also have lower rates of speciation,probably because they have a high capacity for dispersal.

Mike Foote

Prone to extinction

Fluctuate great in diversity

Stabilize diversity

Fluctuate great in diversity

• 107 stages of Phanerozoic • Origination increases diversity and Extinction decreases

diversity BUT

• In Paleozoic diversity increases when extinction had a stronger effect than origination

• In Cenozoic and Mesozoic Origination had a stronger effect than extinction

`THANK YOU!