Transcript Molecular Evolution

Chapter 09
Author: Lee Hannah
FIGURE 9.1 Timeline of Extinction Events. Major extinctions are indicated
by yellow bars. Along with climate change, impacts and volcanic episodes
are leading possible causes of major extinction spasms. Reproduced with
permission from Christopher R. Scotese.
FIGURE 9.2 Major and Minor Extinctions. Diversity of genera over 500 million
years. (A) The red plot shows the number of known marine animal genera versus
time. (B) The black plot shows the same data, with single occurrence and poorly
dated genera removed. The trend line (green) is a third-order polynomial fitted to
the data. (C) Same as B, with the trend subtracted and a 62-Myr sine wave
superimposed. (D) The detrended data after subtraction of the 62-Myr cycle and
with a 140-Myr sine wave superimposed. Dashed vertical lines indicate the times
of the five major extinctions. From Rohde, R. A. and Muller, R. A. 2005. Cycles in
fossil diversity. Nature 434, 208 – 210.
CH009.
FIGURE 9.3 Marine Benthic Habitats Before and After the Permian-Triassic
Extinction Event. A marine fauna of 100 or more species is reduced to less
than 6 species based on seabed reconstructions
off south China. From Benton, M. J., and Twitchett, R. J. 2003. How to kill
(almost) all life: The end-Permian extinction event. Trends in Ecology &
Evolution 18, 358– 365.
FIGURE 9.4 End-Eocene Global Cooling. The initiation of the first permanent
Antarctic ice sheets in the past 100 million years coincided with end-Eocene
cooling, indicated by an arrow at approximately 34 mya. Reproduced with
permission from Yale University Press.
FIGURE 9.5 Methane Outgassing. Methane trapped in sediments as
clathrate may be released in periods of warming. Outgassing from
sediments in the Santa Barbara channel during interglacials is illustrated in
this drawing. Release of methane from clathrates has also been implicated in
rapid warming at the Paleocene – Eocene thermal maximum. Reproduced
with permission from AAAS.
FIGURE 9.6 Species Lost at End-Pleistocene. Some of the dozens of species
lost in North and South America at the end of the Pleistocene are illustrated,
including saber-tooth cats (Smilodon) and wooly mammoth ( Mammuthus
primigenius ). From Wikimedia Commons.
FIGURE 9.7 Declining Mammoth Range. Modeled loss of mammoth range due
to human expansion (dark line) and climate change (color ramp; red most
suitable), from 126,000 years ago to the end of the Pleistocene. From NoguesBravo, D., et al. 2008. Climate change, humans, and the extinction of the woolly
mammoth. PLoS Biology 6, 685 – 692.