BRN 9-2 (uncompressed) - Flipbook - Page 69
The starting point of this study was
the identiÞcation of color morphs in a
stick insect. ÒTimema cristinae is a
wingless, plant-feeding stick insect
that exhibits two color-pattern
morphs that are divergently adapted
to two different plant species. On the
plant Adenostoma fasciculatum, one
often Þnds a striped color-pattern
morph of T. cristinae that is green but
also bears a longitudinal, white stripe
on its dorsal surface. Past work has
shown that this morph is cryptic on
the thin needle-like leaves of A.
fasciculatum. On an alternative host,
the larger and more tree-like
Ceanothus spinosus, one often Þnds
an unstriped morph that is green but
lacks the dorsal stripe, making it
cryptic against the broad leaves of C.
spinosus. Thus, the color-pattern
morphs are adaptations to different
hosts that promote camoußage and
survival in the face of visual predation
by birds and lizards. Both these
morphs are found on two different
mountains (Refugio and Highway
154) near Santa Barbara, California.Ó
In the case of the two study sites the
populations are isolated from each
other and the development of the
morphs appears to have occurred
after the populations became
isolated.
The authors note that ÒThe Þt of
organisms to their environment is a
hallmark of adaptive evolution.
Moreover, such local adaptation can
lead to the emergence of new species
and thus create biological diversity.
The genetic basis of adaptation is of
interest because it can affect the
dynamics of evolution, including its
rate, mode, and repeatability.Ó
The authors performed an extensive
genomic study which included an
assessment of structural variants like
inversion, translocation, and inverted
translocation. They also assessed the
genome position of samples from the
populations. These assessments
supported the concept that the
morphs were of repeated origins, not
from a single origin which then
spread to all populations.
The authors note: ÒWe hypothesize
that structural variation plays a more
important role in evolution than
presently recognized, particularly
because of its diverse effects on
Þtness, such as inßuencing meiosis,
disrupting genes or gene expression
at breakpoints, and capturing
multiple segregating mutations within
inversion haplotypes. Indeed, our
Þndings suggest that structural
variation could be an abundant,
diverse, and widespread source of
genetic variation, providing fuel for
evolution. Moreover, such variation
may arise repeatedly to provide an
element of predictability to adaptive
evolution.Ó
Mackentley, C. M. Neri, B. M.
CanÞeld, and A. R. Lindsay, 2025,
ÒFluorescent pigment concentration
correlated with age, sex, and size in
Long-eared Owl (Asio otus) plumageÓ,
The Wilson Journal of Ornithology,
137(2), 133Ð143. https://doi.org/
10.1080/15594491.2024.2444031).
A warning to those who wish to dive
into this study: it is a bear - unless of
course you have a background in this
Þeld of study. In the last few decades,
there has been a signiÞcant increase
in our understanding of evolutionary
processes and in particular their
complexity and diversity.
The study proposes several reasons
these owls might have ßuorescent
wings. (As an aside, we should note
that the prey [mammals] of these owls
are not known to see in the ultraviolet
spectrum, so they donÕt see the sky
light up with ßuorescence before they
die. Other owls can, however, which
leads to various hypotheses about
dominance and sexual selection.)
Increasingly, there are studies which
argue that the structure and
mechanics of evolution make it easier
for some traits to evolve, and some
argue that this is true to the point of
being predictive. I do not agree with
this line of thought and Þnd it
disturbing. Generally, I Þnd that such
studies suffer from a survivor bias.
Fluorescent Pigmentation
in Long-eared Owls
Emily V. GrifÞth et al. reported on
their study of ßuorescent pigmentation in the feathers of Long-eared
Owls in The Wilson Journal of
Ornithology (E. V. GrifÞth, N.
68
The image above is from the cited
study and shows the ßuorescence of a
Long-eared Owl wing when viewed
with an ultraviolet light.
Dust Storms
On 30 April 2025, Adam Voiland,
writing for the NASA Earth Observatory, noted the assessment of Thomas
Gill, an environmental scientist at the
University of Texas - El Paso. Voiland
wrote that ÒHe said this latest event is
the tenth Ôfull-ßedged dust stormÕ of
the year in El Paso, meaning it was
dusty enough to restrict visibility to
less than half a mile. For comparison,
the average is 1.8 storms per year.
ÔYou would have to go back to 1936 Ñ
during the Dust Bowl Ñ to Þnd a year
with more,Õ Gill said. ÔDuring the
