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Evoluzione orizzontale e ontologia biologica
Emanuele SerrelliPadova, 8-9 maggio 2012
http://www.epistemologia.eu
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Selves
Groups
Earth
Chimeras
Consciousness
3
Selves
4
. . .the “selves” of viruses, utterly depend on their physical contact with bacterial or other living cells. If
not connected to a cell, a virus is as inert as a lump of salt or a cube of sugar. The basic element of life, the
self, is the sensitive bacterial cell; but a virus, as a courier and an integrator of genes into bacteria and
nucleated organisms (animals, plants, fungi and proctotists), can be very important to specific
evolutionary trajectories.(William Day, ch. 2, p. 17)
Selveshttp://jonlieffmd.com/blog/are-viruses-alive-are-viruses-sentient-virus-intelligence
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Selves
http://microbes.nres.uiuc.edu/NRES512.htm
Rymer et al. (2012)
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Selves
http://microbes.nres.uiuc.edu/NRES512.htm
http://microbes.nres.uiuc.edu/NRES512.htm
7
Groups
Ben Jacob et al. (2004)
8
Groups
Bressan (2012)
Groups
9
Murray Bowen photo by Andrea Maloney Schara (1979)http://ideastoaction.wordpress.com/2012/08/29/murray-bowen/
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Chimeras
Chimera di Arezzo, Museo Archeologico, Firenze
Chimeras
12
Vad Drisse (2011)
Chimeras
12
Vad Drisse (2011)
Margulis et al. (2006)
Chimeras
13
Invertebrates...
http://in2uract.wordpress.com/2011/11/24/strengthening-your-immune-system/
Chimeras
14Alves et al.
LemurFamily: Galagidae
http://collections.burkemuseum.org/mtm/images/mtm_slideshows/
3027712362_de1ae16a96_o.jpg
Chimeras
15
Chimeras
16
http://neurosciencefundamentals.unsw.wikispaces.net/The+Neurons+that+Shaped+Our+Worldhttp://www.ted.com/talks/vs_ramachandran_the_neurons_that_shaped_civilization.html
Consciousness
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LemurFamily: Galagidae
http://collections.burkemuseum.org/mtm/images/mtm_slideshows/
3027712362_de1ae16a96_o.jpg
George Mobushttp://faculty.washington.edu/gmobus/Background/evolutionsTrajectory.html
Consciousness
18http://thecampbellgrp.com/glonal-network/
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Selves
Groups
Earth
Chimeras
Consciousness
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For there is, after all, one true tree of life, the unique pattern of evolutionary branchings that
actually happened. It exists. It is in principle knowable. We don’t know it all yet. By 2050 we
should—or if we do not, we shall have been defeated only at the terminal twigs, by the sheer
number of species. ... [H]undreds of separate genes ... are found to corroborate each other’s accounts of the one true tree of life (Dawkins
2003, p. 112; see also Eldredge 2005, p. 227).
23
http://edge.org/conversation/lynn-margulis1938-2011
SET - Serial Endosymbiosis Theory for the origin of eukaryotic cells
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http://img.scoop.co.nz/stories/images/0903/a8de5c88b14851860daa.jpeg
Image courtesy of Lynn Margulis
25http://img.scoop.co.nz/stories/images/0903/a8de5c88b14851860daa.jpeg
Image courtesy of Lynn Margulis
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26
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Virolution at the pro- and eukaryotic level Villarreal & Ryan
28
1957Molecular phylogen.
SSU rRNA (Woese)
19871990s on 2004
29W. Ford Doolittle
1957
In the case of higher plants and animals, species can be grouped into genera, families, and orders on the
basis of their evolutionary relationships, or phylogeny. Such classifications are called natural classifications. In
the bacteria, however, only a few broad lines of evolution are dimly perceivable, and the finer details of
phylogeny remain completely obscure. The existing semiofficial classification of bacteria, Bergey’s Manual, is thus an arbitrary one, and is useful only to the limited
extent that it serves as a ‘‘key’’ for identification.(Steiner et al. 1957)
Phylogeny of bacteria
30W. Ford Doolittle
1957
Phylogeny of bacteria
Molecular phylogen.
phylogenies based on the sequences of ‘‘informational macromolecules’’ are not only more unambiguously
quantifiable but closer to what it is that actually evolves—genes and the genome.
...extend the universal Tree of Life downward to its deepest roots among the prokaryotes
31W. Ford Doolittle
1957
Phylogeny of bacteria
Molecular phylogen.
SSU rRNA (Woese)
32W. Ford Doolittle
1957
Phylogeny of bacteria
Molecular phylogen.
SSU rRNA (Woese)
Lateral, Horizontal gene transfer at the prokaryotic level:
gene donations of bacteria: e.g. resistance of bacteria against antibiotics
32W. Ford Doolittle
1957
Phylogeny of bacteria
Molecular phylogen.
SSU rRNA (Woese)
Lateral, Horizontal gene transfer at the prokaryotic level:
gene donations of bacteria: e.g. resistance of bacteria against antibiotics
...microbiologists had uncovered a phenomenon that might have given them cause to worry that the
evolution of genes might not always be tree-like, and that gene trees might not always be species trees.
33W. Ford Doolittle
1957
Phylogeny of bacteria
Molecular phylogen.
SSU rRNA (Woese)Why few of us thought that LGT would
interfere seriously with universal tree construction is an interesting question for
the historian and sociologist...
34W. Ford Doolittle
1957
Phylogeny of bacteria
Molecular phylogen.
SSU rRNA (Woese)
1987
In the extreme, interspecies exchanges of genes could be so rampant, so broadspread, that a bacterium would not actually have a history in its own right; it would be an evolutionary chimera, a
collection of genes (or gene clusters), each with its own
history...
35W. Ford Doolittle
1957
Phylogeny of bacteria
Molecular phylogen.
SSU rRNA (Woese)
1987
Fortunately the matter is experimentally decidable.
Were an organism an evolutionary chimera, then its various chronometers would yield different, conflicting
phylogenies.
36W. Ford Doolittle
1957
Phylogeny of bacteria
Molecular phylogen.
SSU rRNA (Woese)
19871990s on
37W. Ford Doolittle
1957
Phylogeny of bacteria
Molecular phylogen.
SSU rRNA (Woese)
19871990s on
Assessing how many of a genomes’ genes have been laterally transferred at some time in its history will always be technically difficult and fraught with definitional problems, although few would now claim that the fraction is less than
one half, and many would accept that it is more than 95%. It turns out to be simpler to ask how many and which genes might possibly have
avoided LGT in the last four billion years.
38W. Ford Doolittle
1957
Phylogeny of bacteria
Molecular phylogen.
SSU rRNA (Woese)
19871990s on
39W. Ford Doolittle
1957
Phylogeny of bacteria
Molecular phylogen.
SSU rRNA (Woese)
19871990s on
40
Network diagrams combines both horizontal and vertical evolutionary events in prokaryotes Dagan and Martin, 2009: 2190
41
Margulis
Symbiogenesis
1957Molecular phylogen.
SSU rRNA (Woese)
19871990s on
42
Margulis
Symbiogenesis
1957Molecular phylogen.
SSU rRNA (Woese)
19871990s on
Symbiogenesis
43
http://img.scoop.co.nz/stories/images/0903/a8de5c88b14851860daa.jpeg
Image courtesy of Lynn Margulis
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Margulis
Symbiogenesis
1957Molecular phylogen.
SSU rRNA (Woese)
19871990s on
Original formulation of symbiosis theory
by Constantin Mereschkowsky
1909
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How many individuals ? How many kinds of individuals?
19
We need better definitions of individuals
Courtesy of Fred Bouchhard, 2013
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MaureenO’Malley
Centrality of Biological species and their tree
1957Molecular phylogen.
SSU rRNA (Woese)
19871990s on
Ernst Mayr, the tree of life, and philosophy of biology
Maureen A. O’Malley
Published online: 8 May 2010! Springer Science+Business Media B.V. 2010
Abstract Ernst Mayr’s influence on philosophy of biology has given the field aparticular perspective on evolution, phylogeny and life in general. Using debatesabout the tree of life as a guide, I show how Mayrian evolutionary biology excludesnumerous forms of life and many important evolutionary processes. Hybridizationand lateral gene transfer are two of these processes, and they occur frequently, withimportant outcomes in all domains of life. Eukaryotes appear to have a more tree-like history because successful lateral events tend to occur among more closelyrelated species, or at a lower frequency, than in prokaryotes, but this is a differenceof degree rather than kind. Although the tree of life is especially problematic as arepresentation of the evolutionary history of prokaryotes, it can function moregenerally as an illustration of the limitations of a standard evolutionary perspective.Moreover, for philosophers, questions about the tree of life can be applied to theMayrian inheritance in philosophy of biology. These questions make clear that thedichotomy of life Mayr suggested is based on too narrow a perspective. An alter-native to this dichotomy is a multidimensional continuum in which differentstrategies of genetic exchange bestow greater adaptiveness and evolvability on pro-karyotes and eukaryotes.
Keywords Ernst Mayr ! Philosophy of biology ! Evolution ! Tree of life !Species ! Lateral gene transfer ! Hybridization
Introduction
Most philosophers of biology have in the back of their mind at least a vague image ofa tree of life that depicts bifurcating species lineages and represents the evolutionary
M. A. O’Malley (&)Egenis, University of Exeter, St Germans Road, EX4 4PJ Exeter, UKe-mail: M.A.O’[email protected]
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Biol Philos (2010) 25:529–552DOI 10.1007/s10539-010-9214-6
47
MaureenO’Malley
Centrality of Biological species and their tree
1957Molecular phylogen.
SSU rRNA (Woese)
19871990s on 2004
All so-called asexually reproducing organisms do not have species.
The prokaryotes are difficult enough [to deal with], but even
when you get into the low eukaryotes, there is this group that is a sort of a garbage can called the protists. And there are authors I’m told that recognize 80 phyla of protists. God knows what there is
in these 80 phyla. And most of them do not have species in the normal sense. They don’t have a proper process of speciation or
anything like that.
48But again, on the pragmatic grounds of removing the messier, more web-like
evolutionary patterns such processes produce, we could conclude that Mayr isjustified in excluding protists (along with prokaryotes) for not having reproductivelyisolated species. Representations of evolution would have to encompass multipleprocesses and entities, and trees would become very difficult to construct ifdisorderly organisms were to be admitted. But if evolutionary systematists arewilling to discard protists, the same logic that allows this exclusion will have toallow the omission of even more eukaryotes from mainstream evolutionaryunderstanding.
Fungi
Fungi are highly diverse and prolific entities, ranging from single-celled organisms(e.g. yeast, moulds) to gigantic clones many hectares in dimension (Smith et al.1992; Bendel et al. 2006). The full extent of their diversity is still unknown, but it isthought to be at the level of insects (Hawksworth 2001; McLaughlin et al. 2009).Mayr tended to ignore fungi or to lump them into discussions of protists, eventhough he was impressed by the fact that fungi were eventually recognized as closerto animals than plants (1998b). His lack of attention to them was probably due to the
Fig. 1 Six eukaryote supergroups. Reprinted from Lane and Archibald (2008), with permission fromElsevier
538 M. A. O’Malley
123
From Lane and Archibald (2008), in O’Malley 2010
MaureenO’Malley
there is growing evidence of gene exchange in protists (Keeling and Palmer 2008; Andersson 2009). Sequence analyses of several protist genomes have detected bacterial genes in varying amounts, with as
much as 4% of rumen ciliate genomes being of foreign origin (Ricard et al. 2006). In the genome of the miniscule green alga, Ostreococcus tauri, the
smallest free-living eukaryote, a whole chromosome appears to have been acquired, although its source is not obvious (Derelle et al. 2006). The
pathogens Giardia lamblia, Trichomonas vaginalis, and Entamoeba histolytica have ‘borrowed’ large numbers of virulence and metabolism genes from bacteria (Andersson et al. 2006; Loftus et al. 2005). Transfers between protists, and from other eukaryotes to protists, have also been found in increasing numbers, and the data for such acquisitions increase with every genome sequence deposited in GenBank or other databases (Andersson 2009). The more lateral gene transfer in protists is studied, in fact, the more that is learned about interdomain exchange as an ongoing
evolutionary mechanism of genetic diversity (Andersson et al. 2006).
48But again, on the pragmatic grounds of removing the messier, more web-like
evolutionary patterns such processes produce, we could conclude that Mayr isjustified in excluding protists (along with prokaryotes) for not having reproductivelyisolated species. Representations of evolution would have to encompass multipleprocesses and entities, and trees would become very difficult to construct ifdisorderly organisms were to be admitted. But if evolutionary systematists arewilling to discard protists, the same logic that allows this exclusion will have toallow the omission of even more eukaryotes from mainstream evolutionaryunderstanding.
Fungi
Fungi are highly diverse and prolific entities, ranging from single-celled organisms(e.g. yeast, moulds) to gigantic clones many hectares in dimension (Smith et al.1992; Bendel et al. 2006). The full extent of their diversity is still unknown, but it isthought to be at the level of insects (Hawksworth 2001; McLaughlin et al. 2009).Mayr tended to ignore fungi or to lump them into discussions of protists, eventhough he was impressed by the fact that fungi were eventually recognized as closerto animals than plants (1998b). His lack of attention to them was probably due to the
Fig. 1 Six eukaryote supergroups. Reprinted from Lane and Archibald (2008), with permission fromElsevier
538 M. A. O’Malley
123
From Lane and Archibald (2008), in O’Malley 2010
MaureenO’Malley
49But again, on the pragmatic grounds of removing the messier, more web-like
evolutionary patterns such processes produce, we could conclude that Mayr isjustified in excluding protists (along with prokaryotes) for not having reproductivelyisolated species. Representations of evolution would have to encompass multipleprocesses and entities, and trees would become very difficult to construct ifdisorderly organisms were to be admitted. But if evolutionary systematists arewilling to discard protists, the same logic that allows this exclusion will have toallow the omission of even more eukaryotes from mainstream evolutionaryunderstanding.
Fungi
Fungi are highly diverse and prolific entities, ranging from single-celled organisms(e.g. yeast, moulds) to gigantic clones many hectares in dimension (Smith et al.1992; Bendel et al. 2006). The full extent of their diversity is still unknown, but it isthought to be at the level of insects (Hawksworth 2001; McLaughlin et al. 2009).Mayr tended to ignore fungi or to lump them into discussions of protists, eventhough he was impressed by the fact that fungi were eventually recognized as closerto animals than plants (1998b). His lack of attention to them was probably due to the
Fig. 1 Six eukaryote supergroups. Reprinted from Lane and Archibald (2008), with permission fromElsevier
538 M. A. O’Malley
123
From Lane and Archibald (2008), in O’Malley 2010
MaureenO’Malley
In fungi, there is a growing list of what seem to be fungal hybrids (Schardl and Craven 2003; Novo et al. 2009). Moreover, there appears to be a great deal of LGT occurring between prokaryotes and fungi, between
fungal lineages, and between fungi and other multicellular eukaryotes (e.g. Schardl and Craven 2003; Friesen et al. 2006; Richards et al. 2006,
2009). Numerous phylogenetically discordant plasmids, transposons and gene clusters have been detected in a range of fungal lineages, and even
some whole chromosome transfers between filamentous fungi (Walton 2000). In addition, there is good experimental evidence of
transformation (uptake of environmental DNA) in a few fungi (Rosewich and Kistler 2000). Whether novel DNA is acquired by hybridization or by LGT, it has either to be excluded from phylogenetic analysis or depicted
as a reticulate event.
50But again, on the pragmatic grounds of removing the messier, more web-like
evolutionary patterns such processes produce, we could conclude that Mayr isjustified in excluding protists (along with prokaryotes) for not having reproductivelyisolated species. Representations of evolution would have to encompass multipleprocesses and entities, and trees would become very difficult to construct ifdisorderly organisms were to be admitted. But if evolutionary systematists arewilling to discard protists, the same logic that allows this exclusion will have toallow the omission of even more eukaryotes from mainstream evolutionaryunderstanding.
Fungi
Fungi are highly diverse and prolific entities, ranging from single-celled organisms(e.g. yeast, moulds) to gigantic clones many hectares in dimension (Smith et al.1992; Bendel et al. 2006). The full extent of their diversity is still unknown, but it isthought to be at the level of insects (Hawksworth 2001; McLaughlin et al. 2009).Mayr tended to ignore fungi or to lump them into discussions of protists, eventhough he was impressed by the fact that fungi were eventually recognized as closerto animals than plants (1998b). His lack of attention to them was probably due to the
Fig. 1 Six eukaryote supergroups. Reprinted from Lane and Archibald (2008), with permission fromElsevier
538 M. A. O’Malley
123
From Lane and Archibald (2008), in O’Malley 2010
MaureenO’Malley
They can combine sexual and asexual reproduction (with sexual reproduction being the ancient state, since lost in many lineages), and it is
still sometimes unclear how particular fungi reproduce (Petersen and Hughes 1999; Schardl and Craven 2003; Zeyl 2009). One reproductive
peculiarity of fungi involves hyphal fusion, in which fungal filaments anastomose parasexually, through somatic recombination rather than
germ cell recombination. Large numbers of nuclei (sometimes thousands) from the different hyphae share the same enlarged cell compartment. In many lineages, interspecific matings are vegetatively incompatible, which means that the non-self recognition of introduced genetic systems results in the destruction of the newly merged hyphal cells (Glass and Dementhon 2006; Glass and Kaneko 2003; Giraud et al. 2008). Even when this does
not happen, the heterokaryon products of hyphal fusion (cells with different genotypes) may be unstable and produce only homokaryotic offspring. But this is not always the case, and nor does incompatibility
recognition happen for all hyphal fungi.
51But again, on the pragmatic grounds of removing the messier, more web-like
evolutionary patterns such processes produce, we could conclude that Mayr isjustified in excluding protists (along with prokaryotes) for not having reproductivelyisolated species. Representations of evolution would have to encompass multipleprocesses and entities, and trees would become very difficult to construct ifdisorderly organisms were to be admitted. But if evolutionary systematists arewilling to discard protists, the same logic that allows this exclusion will have toallow the omission of even more eukaryotes from mainstream evolutionaryunderstanding.
Fungi
Fungi are highly diverse and prolific entities, ranging from single-celled organisms(e.g. yeast, moulds) to gigantic clones many hectares in dimension (Smith et al.1992; Bendel et al. 2006). The full extent of their diversity is still unknown, but it isthought to be at the level of insects (Hawksworth 2001; McLaughlin et al. 2009).Mayr tended to ignore fungi or to lump them into discussions of protists, eventhough he was impressed by the fact that fungi were eventually recognized as closerto animals than plants (1998b). His lack of attention to them was probably due to the
Fig. 1 Six eukaryote supergroups. Reprinted from Lane and Archibald (2008), with permission fromElsevier
538 M. A. O’Malley
123
From Lane and Archibald (2008), in O’Malley 2010
MaureenO’Malley
study after study has documented the adaptiveness and proliferation of plant hybrids (Heiser 1973; Arnold 2006; Arnold et al. 1999; Soltis and
Soltis 2009). Much known hybridization involves genome doubling (allopolyploidy), which has played a major role in plant evolution (Adams
and Wendel 2005). Other hybridization events involve genome recombination (homoploidy). An example of the latter, which is more
difficult to detect, is provided by the sunflowers Helianthus annuus and H. petiolaris. These parental species have three hybrid offspring (H.
anomalus, H. deserticola, and H. paradoxus) that evolved between 60,000 and 200,000 years ago. While the parent plants favour temperate climates, the hybrid offspring inhabit and flourish in extreme environments,
such as harsh desert conditions and salt marshes (Rieseberg 1997; Rieseberg et al. 2003). It is frequently the case that hybrid offspring have hardier characteristics than their parents, due to new gene combinations that allow the hybrids to colonize new ecological niches (Rieseberg and
Willis 2007).
52But again, on the pragmatic grounds of removing the messier, more web-like
evolutionary patterns such processes produce, we could conclude that Mayr isjustified in excluding protists (along with prokaryotes) for not having reproductivelyisolated species. Representations of evolution would have to encompass multipleprocesses and entities, and trees would become very difficult to construct ifdisorderly organisms were to be admitted. But if evolutionary systematists arewilling to discard protists, the same logic that allows this exclusion will have toallow the omission of even more eukaryotes from mainstream evolutionaryunderstanding.
Fungi
Fungi are highly diverse and prolific entities, ranging from single-celled organisms(e.g. yeast, moulds) to gigantic clones many hectares in dimension (Smith et al.1992; Bendel et al. 2006). The full extent of their diversity is still unknown, but it isthought to be at the level of insects (Hawksworth 2001; McLaughlin et al. 2009).Mayr tended to ignore fungi or to lump them into discussions of protists, eventhough he was impressed by the fact that fungi were eventually recognized as closerto animals than plants (1998b). His lack of attention to them was probably due to the
Fig. 1 Six eukaryote supergroups. Reprinted from Lane and Archibald (2008), with permission fromElsevier
538 M. A. O’Malley
123
From Lane and Archibald (2008), in O’Malley 2010
MaureenO’Malley
One classic study that did not quite fit Mayr’s expectations was carried out by Lewontin and L. C. Birch (1966). They argued that hybridization was a source of
variation for adaptation to new environments in particular groups of Queensland fruit flies (then Dacus, now Bactrocera tryoni and B. neohumeralis)...
...because hybridization is usually investigated in relation to visibly distinguishable taxa, it has probably been systematically underestimated in duller, more uniform types of organisms such as little brown birds or butterflies (Mallet 2005; Dowling and Secor
1997). Some classic examples include ducks (much collected during hunting seasons, and therefore well observed), birds of paradise, cichlids and butterflies
(see Mallet et al. 2007). Cichlids and other freshwater fish are well known for their hybridization capacities, partly because of the very divergent morphologies and colour
patterns produced by introgression (Koblmüller et al. 2007). In representing these introgressions phylogenetically, many branches have to be reticulated to make sense
of incongruent gene phylogenies.Although there may be low levels of fertility in the first generation of hybrids, later
generations frequently stabilize, often with fitness advantages in new or expanded environments (Anderson 1948; Arnold 2006). And although rates of hybridization may be low, they can have major evolutionary consequences (Seehausen 2004; Dowling
and Secor 1997).
53
Virolution at the pro- and eukaryotic level Villarreal & Ryan
53
Virolution at the pro- and eukaryotic level Villarreal & Ryan
Much of the known LGT in animals involves acquisitions from prokaryotes, such as genes for cellulose biosynthesis in marine invertebrates, and glyoxylate-cycle enzymes in a number of animals (Nakashima et al. 2004; Kondrashov et al. 2006).
The genomes of Wolbachia-infected insects can carry large fragments of Wolbachia DNA— nearly a whole Wolbachia genome in one case (Hotopp et al.
2007).An even more intriguing example of animal LGT is that of bdelloid rotifers (a
microscopic multicellular aquatic animal), the genomes of which show evidence of recent and ancient acquisitions of bacterial, fungal, and plant genes (Gladyshev et al. 2008). Rotifers have a life cycle that can include dessication, and as the dessicated
body revives in the presence of water, environmental DNA seems to be integrated into the rotifer’s genome through a combination of membrane damage and DNA repair
mechanisms, and then inherited in the absence of sexual recombination. Most of the intact foreign genes code for simple enzymatic functions such as carbohydrate
decomposition (rather than multi- component biochemical pathways)...Some plant-parasitic nematodes have acquired bacterial genes that enable the
nematodes to modify plant cell walls, thereby damaging the plant but nourishing the nematode (Scholl et al. 2003).
54
MaureenO’Malley
Centrality of Biological species and their tree
1957Molecular phylogen.
SSU rRNA (Woese)
19871990s on 2004
55
HybridizationSchwenk et al. (2008)
56
Hybridization
1957Molecular phylogen.
SSU rRNA (Woese)
19871990s on 2004
57
Animal (and plant) evolution Representative Well represented
by tree Impact on TOL
Mayr Yes Yes -
Doolittle No Yes Circumscribe
Margulis No No Replace
O’Malley No No Multidimensional space
Hybrid. studies N/A (yes) Yes Speciation and adaptation mech.
58
Animal (and plant) evolution Representative Well represented
by tree Impact on TOL
Mayr Yes Yes -
Doolittle No Yes Circumscribe
Margulis No No Replace
O’Malley No No Multidimensional space
Hybrid. studies N/A (yes) Yes Speciation and adaptation mech.
58
evolution of multicellular animals and plants can still be
well understood as a branching process (albeit with some
fuzziness)
prokaryotic evolution may be better modeled as a reticulated web. This is because prokaryotes (bacteria and
archaea) much more readily exchange genes ‘‘across species lines’’, by several genetic mechanisms collectively known
as lateral gene transfer (LGT). Since prokaryotes comprise the majority of living things, and since the first two-thirds of Life’s history is exclusively prokaryotic, the TOL is of limited
explanatory scope.
59
Animal (and plant) evolution Representative Well represented
by tree Impact on TOL
Mayr Yes Yes -
Doolittle No Yes Circumscribe
Margulis No No Replace
O’Malley No No Multidimensional space
Hybrid. studies N/A (yes) Yes Speciation and adaptation mech.
A key residual question from the discussion above is whether evolutionary biology and its philosophy should follow
Mayr and split evolution into two types: the processes and outcomes that occur with ‘good’ speciators, and those that occur
with ‘bad’ speciators...a continuum perspective is the only
remaining optionmultiple intersecting continua: asexual-
sexual, much-less-exchange, uni-multicellular...
an approach along these lines would be more informative than a focus on which organisms have evolved in tree-like patterns. A
multidimensional approach by no means rejects the importance of such patterns, nor of the processes that gave rise to them, but it sees them as just one possible focus and not always the most
valuable one.
?
References
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