m.r.Life ι**=7/3ψ

Evolutionary Biology Blog


The time bend of curved allometries

Another challenge to our understanding of body mass evolution is the finding that the most studied allometry, i.e., the relationship between basal metabolism and mass in mammals, is not a straight line on the double logarithmic plot, but a convexly bend curve (Kolokotrones et al., 2010). Does this curvature reflect a bug in our theory, or is it simply a logical consequence of the natural selection of mass?

This is examined in a new release on bioRxiv ... Read More


Body mass evolution bend by time

In a new release on bioRxiv I use the “allometries are selected by the selection of metabolism and mass”-hypothesis (Witting, 2016a) to study the evolution of body mass and allometries in time. This shows how a contraction of natural selection time from the primary selection of metabolism, and a dilation of natural selection time from the primary selection of mass, are explaining four different bends of body mass evolution in the fossil record.

Unconstrained population dynamic feed-back selection predicts ... Read More


From replicating molecules to multicellular animals

In a new release on bioRxiv (Witting, 2016b) I integrate an initial mass dependence of mass specific metabolism into the “allometries are selected by the selection of metabolism and mass”-hypothesis (Witting, 2016a). This shows that a decline in the importance of mass specific metabolism for the selection of mass, and an associated unfolding of interactive competition, select for lifeforms from virus over prokaryotes and larger unicells to multicellular animals with sexual reproduction between female and male individuals.

All organisms have ... Read More


Metabolism, mass and allometric transitions

In a new release on bioRxiv, I take the original “allometries are selected by the selection of mass”-hypothesis (Witting, 1995, 1997) and integrate primary selection on mass specific metabolism into the selection of mass. This shows how a change in the importance of mass specific metabolism for the selection of mass is explaining allometric transitions from prokaryotes over larger unicells to multicellular animals.

The study finds that mass specific metabolism is selected ... Read More


Back on the allometric track

Major lifeforms like those of virus, prokaryotes, unicellular eukaryotes and multicellular animals fall in distinct size classes, with distinct allometric profiles. The natural selection of these allometric transitions with mass may thus explain the evolution of the major lifeforms.

By having no intrinsic metabolism, viruses have evolved beyond ... Read More


Mass-transitions in asexual lifeforms

With the primary selection of net energy and mass explaining allometries and major life history transitions, we can predict the evolution of complex Earth-like organisms from the origin of self-replicating entities. But there are unexplained transitions in the mass of asexual lifeforms, and this suggests that the theory is incomplete. ... Read More


Permanent interactions in sessile lifeforms

Some of the major transitions are found only in mobile organisms. Co-operate breeding and eusocial colonies are absent in sessile organisms, and their sexual reproduction is of another kind where it often occurs between hermaphrodites, and not between male and female individuals.

These differences are selected by ... Read More


Mass selects population dynamic equations

Because of its ability to determine the level of interference competition in the population, it is the selection of mass that determines the abundance of the population dynamic equilibrium.

This makes the population dynamic equilibrium a ... Read More


Mass selects major evolutionary transitions

Because of its ability to determine the level of interference competition in the population, it is the selection on mass that determines the evolutionary fate of the organism.

This is seen across the tree of life ... Read More


Mass selects intra-specific interference

With interactive competition selecting net energy into interactive quality, we need to predict the level of interference in order to predict the course of evolution. And for this we need to understand the natural selection on mass.

We have already seen ... Read More


The beauty of natural selection simplicity

The potentially simplest mechanism for a causal theory of evolution is the intrinsic selection that emerges from heritable difference in the rate of self-replication. This route, however, is unlikely to be productive ... Read More


The need for evolutionary determinism

Think of the evolution of the physical Universe; and then of biological evolution.

For the Universe, you probably have a clear view; a big-bang that created an expanding universe, where gravity pulls inert matter into stars and planets, with the gravity of stars initialising a nuclear fusion that produces light and heavier atoms from hydrogen.

For biology you might see nothing but mist ... Read More


The collapse of evolutionary theory

The confirmation of evolutionary theory by empirical observation is essential. But how can we get an evolutionary theory confirmed when the predicted fitness covariance cannot in principle confirm the assumed causality due to the pitfall of evolutionary interpretation?

A way forward is to raise the bar of what is required theoretically for an evolutionary theory to work ... Read More ... #3 for inspiration at #Evol2016

[ blog-posts on the rebuilding of evolutionary theory starts in August ]


The just-so stories of biological evolution

It is sad to say, but the majority of our natural selection causality from evolutionary theory is really just just-so stories, where a pseudo form of evolutionary contingency is likely to produce ad hoc fallacies by the pitfall of evolutionary interpretation.

There is, of course, plenty of real contingency in biological evolution. This is of the ... Read More ... #2 for inspiration at #Evol2016


The pitfall of evolutionary interpretation

Observations of fitness differences in populations in connections with evolutionary experiments are essential for a detailed understanding of selection in natural populations; yet, these observations have misguided evolutionary biologists for decades.

The best example is maybe brood size manipulation, that was first introduced by Lack in 1947. By enhancing the number of eggs in some bird nests, and reducing them in others, these experiments show ... Read More ... #1 for inspiration at #Evol2016


The selection of mass selects allometries

The importance of allometries for evolutionary biology is hard to overestimate as they show how the life history is co-evolving with body mass across the tree of life.

But it has been frustrating to see the field lose focus. It started promising with a surface rule (Rubner, 1883), and Kleiber's (1932) suggestion that the “real” exponent for total metabolism is closer to 3/4, than 2/3. I joined the game in 1995 when there were no general explanation, and showed that the 3/4 exponent is explained by the optimisation of the interactive competition that selects for the evolution of non-negligible body masses (Witting, 1995, 1997).

A few years later, we got West, Brown and Enquist's (1997, 1999) study in Science and Nature that missed the point ... Read More