In the Light of Evolution Volume II: Biodiversity and Extinction (2008) / Chapter Skim
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13 A Phylogenetic Perspective on the Distribution of Plant Diversity--MICHAEL J. DONOGHUE
13 A Phylogenetic Perspective on the Distribution of Plant Diversity--MICHAEL J. DONOGHUE
Pages 247-262
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From page 247... ...
Phylogenetic niche conservatism has important consequences for the assembly of both local communities and the regional species pools from which these are drawn. If corridors for movement are available, newly emerging environments will tend to be filled by species that filter in from areas in which the relevant adaptations have already evolved, as opposed to being filled by in situ evolution of these adaptations.
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From page 248... ...
For example, Arthur Cronquist, the prime architect of angiosperm classification in that era (from the 1960s through the 1980s) , pointed out repeatedly that higher taxa were not readily characterized by particular ecological roles: ‘‘Each of the obvious ecological niches for land plants is occupied by species representing diverse families and orders. . . .
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From page 249... ...
That is, he argued that owing ultimately to limited functional and developmental integration in plants, vegetative traits related to climate tolerances were highly labile and only rarely marked higher taxa. In fact, his main thesis depended directly on the rapidity with which transitions between major climate zones could occur.
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From page 250... ...
After all, major clades within angiosperms, despite significant ecological diversity, hardly occupy all possible environments, but instead are restricted to one or a few major biomes, such as tropical rainforests, temperate forests, grassland, or deserts. Despite the great variety of environments occupied by the Asteraceae, for example, they are far more common in arid environments than they are in tropical forests.
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From page 251... ...
Recent phylogenetic studies have simply focused new light on the existence and the global importance of key ecological traits at the more conservative end of this distribution. My concentration here on the conserved end of the distribution is in no way meant to question the reality or significance of highly labile ecological traits, the evolution of which surely underlie many ecological adjustments.
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From page 252... ...
A key ingredient of this argument, which led John Wiens and I to call it the ‘‘tropical niche conservatism'' hypothesis (Wiens and Donoghue, 2004) , is that not all tropical lineages confronted with the retraction of tropical climates during the Tertiary managed to adapt to colder climates.
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From page 253... ...
reasoned, where abiotic habitat filtering is the dominant force shaping coexistence, PNC should result in phylogenetic clustering in the phylogeny of the regional species pool. On the other hand, where biotic competitive exclusion is the dominant ecological force, PNC should result in a more even (overdispersed)
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From page 254... ...
NICHE CONSERVATISM AND REGIONAL SPECIES POOLS A less well appreciated role of phylogenetic niche conservatism, and the one that I especially want to highlight here, concerns the composition of the regional species pools from which local communities become assembled. In my view the most compelling studies to date along these lines have been carried out in Mediterranean climate systems, by Miguel Verdu et al.
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From page 255... ...
If, when climate change occurs, suitable corridors exist for the dispersion of species with relevant traits, these lineages will tend to track the habitat to which they are adapted and move into the region relatively quickly, perhaps preempting the in situ evolution of these traits among the natives. Under these circumstances, it is the sorting or filtering of species into the region that will dominate the assembly of the regional species pool.
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From page 256... ...
Here, I briefly highlight three biodiversity phenomena in flowering plants that variously reflect the interaction of niche conservatism with environmental changes through the Tertiary (Fig.
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From page 257... ...
A -30° -30° -60° -60° FIGURE 13.1 Major patterns in the movement of plant lineages discussed here.
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From page 258... ...
Second, just as only some tropical lineages adapted to temperate climates, only some temperate plant lineages adapted to even colder climates that would have allowed their continuous distribution through Beringia, even today. It is also noteworthy that few temperate-adapted plant lineages appear to have moved back into truly tropical climates, although in this case competition may also have played an important role.
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From page 259... ...
However, it remains unclear how many resident South American plant lineages living at lower, warmer elevations, gave rise to Andean alpine plants (e.g., Espeletia, Asteraceae; Puya, Bromeliaceae)
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From page 260... ...
In short, I am agreeing with Robert Ricklefs (2004) that we should ‘‘raise regional and historical factors to equal footing with local determinism in their influence on the diversity–environment relationship and geographical patterns of diversity in general.'' Fortunately, whereas the integration of phylogenetic knowledge into such explanations once seemed unnecessary, and for a time seemed interesting but impractical, now it seems virtually inevitable.
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From page 261... ...
Moore for an insightful critique of the manuscript; and members of the Scientific Committee of the bioGENESIS program within DIVERSITAS. My work on angiosperm phylogeny and biogeography has been supported recently by the National Science Foundation through two Assembling the Tree of Life grants, Cyberinfrastructure for Phylogenetic Research, and the National Evolutionary Synthesis Center Northern Hemisphere Phytogeography Working Group.
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