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other clades to extinction. A corollary of this
view is that current biodiversity must be
higher than it has ever been. Limits to infinite
growth are clearly local, regional, and global
turnover and extinction events, when climate
change and physical catastrophes knock out
species and whole clades, and push the rising
exponential curve down a notch or two.
2008010009
远 古 时 期 的 宏 演 化 和 宏 生 态 学 = Macroevolution
and macroecology through deep time.
( 英 文 ). Butterfield N J. Palaeontology, 2007,
50(1): 41-55
The fossil record documents two mutually
exclusive macroevolutionary modes separated
by the transitional Ediacaran Period. Despite
the early appearance of crown eukaryotes and
an at least partially oxygenated atmosphere,
the pre-Ediacaran biosphere was populated
almost exclusively by microscopic organisms
exhibiting low diversity, no biogeographical
partitioning and profound morphological/evolutionary
stasis. By contrast, the post-
Ediacaran biosphere is characterized by large
diverse organisms, bioprovinciality and conspicuously
dynamic macroevolution. The difference
can be understood in terms of the
unique escalatory coevolution accompanying
the early Ediacaran introduction of eumetazoans,
followed by their early Cambrian (Tommotian)
expansion into the pelagic realm.
Eumetazoans reinvented the rules of macroecology
through their invention of multitrophic
food webs, large body size, life-history
trade-offs, ecological succession, biogeography,
major increases in standing biomass, eukaryote-dominated
phytoplankton and the potential
for mass extinction. Both the pre-
Ediacaran and the post-Ediacaran biospheres
were inherently stable, but the former derived
from the simplicity of superabundant microbes
exposed to essentially static, physical environments,
whereas the latter is based on
eumetazoan-induced diversity and dynamic,
biological environments. The c. 100-myr
Ediacaran transition (extending to the base of
the Tommotian) can be defined on evolutionary
criteria, and might usefully be incorporated
into the Phanerozoic.
2008010010
差 异 : 形 态 学 模 式 和 发 育 背 景 = Disparity:
morphological pattern and developmental context.
( 英 文 ). Erwin D H. Palaeontology, 2007,
50(1): 57-73
The distribution of organic forms is clumpy
at any scale from populations to the highest
taxonomic categories, and whether considered
within clades or within ecosystems. The fossil
record provides little support for expectations
that the morphological gaps between species
or groups of species have increased through
time as it might if the gaps were created by
extinction of a more homogeneous distribution
of morphologies. As the quantitative assessments
of morphology have replaced counts of
higher taxa as a metric of morphological disparity,
numerous studies have demonstrated
the rapid construction of morphospace early in
evolutionary radiations, and have emphasized
the difference between taxonomic measures of
morphological diversity and quantitative assessments
of disparity. Other studies have
evaluated changing patterns of disparity across
mass extinctions, ecomorphological patterns
and the patterns of convergence within ecological
communities, while the development
of theoretical morphology has greatly aided
efforts to understand why some forms do not
occur. A parallel, and until recently, largely
separate research effort in evolutionary developmental
biology has established that the developmental
toolkit underlying the remarkable
breadth of metazoan form is largely identical
among Bilateria, and many components are
shared among all metazoa. Underlying this
concern with disparity is a question about
temporal variation in the production of morphological
innovations, a debate over the relative
significance of the generation of new
morphologies vs. differential probabilities of
their successful introduction, and the relative
importance of constraint, convergence and
contingency in the evolution of form.
2008010011
宏 演 化 不 同 于 持 续 的 微 演 化 吗 = Is
macroevolution more than successive rounds
of microevolution. ( 英 文 ). Grantham T. Palaeontology,
2007, 50(1): 75-85
Whether macrovolution is reducible to
microevolution is one of the persistent debates
in evolutionary biology. Although the concept
of emergence is important to answering this
question, it has not been extensively discussed
within palaeobiology. A taxonomy of emergence
concepts is presented to clarify the ways
in which emergence relates to this debate.
Weak emergence is a particularly helpful way
to understand the hierarchical nature of biology:
it captures the ways in which higher-level
traits depend on lower-level processes, while
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