Biology subjects

David Morrison

Publications and source records attributed to David Morrison.

3 recordsLinked to original sources

bioRxiv2014

Are phylogenetic patterns the same in anthropology and biology?

The use of phylogenetic methods in anthropological fields such as archaeology, linguistics and stemmatology (involving what are often called \"culture data\") is based on an analogy between human cultural evolution and biological evolution. We need to understand this analogy thoroughly, including how well anthropology data fit the model of a phylogenetic tree, as used in biology. I provide a direct comparison of anthropology datasets with both phenotype and genotype datasets from biology. The anthropology datasets fit the tree model approximately as well as do the genotype data, which is detectably worse than the fit of the phenotype data. This is true for datasets with <500 parsimony-informative characters, as well as for larger datasets. This implies that cross-cultural (horizontal) processes have been important in the evolution of cultural artifacts, as well as branching historical (vertical) processes, and thus a phylogenetic network will be a more appropriate model than a phylogenetic tree.

Evolutionary Biology↗

bioRxiv2014

Estimating seed bank accumulation and dynamics in three obligate-seeder Proteaceae species

The seed bank dynamics of the three co-occurring obligate-seeder (i.e. fire-sensitive) Proteaceae species, Banksia ericifolia, Banksia marginata and Petrophile pulchella, were examined at sites of varying time since the most recent fire (i.e. plant age) in the Sydney region. Significant variation among species was found in the number of cones produced, the position of the cones within the canopy, the percentage of barren cones produced (Banksia species only), the number of follicles/bracts produced per cone, and the number of seeds lost/released due to spontaneous fruit rupture. Thus, three different regeneration strategies were observed, highlighting the variation in reproductive strategies of co-occurring Proteaceae species. Ultimately, B. marginata potentially accumulated a seed bank of [~]3000 seeds per plant after 20 years, with [~]1500 seeds per plant for P. pulchella and [~]500 for B. ericifolia. Based on these data, B. marginata and B. ericifolia require a minimum fire-free period of 8-10 years, with 7-8 years for P. pulchella, to allow for an adequate seed bank to accumulate and thus ensure local persistence of these species in fire-prone habitats.

Ecology↗

bioRxiv2014

How and where to look for tRNAs in Metazoan mitochondrial genomes, and what you might find when you get there

The ability to locate and annotate mitochondrial genes is an important practical issue, given the rapidly increasing number of mitogenomes appearing in the public databases. Unfortunately, tRNA genes in Metazoan mitochondria have proved to be problematic because they often vary in number (genes missing or duplicated) and also in the secondary structure of the transcribed tRNAs (T or D arms missing). I have performed a series of comparative analyses of the tRNA genes of a broad range of Metazoan mitogenomes in order to address this issue. I conclude that no single computer program is necessarily capable of finding all of the tRNA genes in any given mitogenome, and that use of both the ARWEN and DOGMA programs is sometimes necessary because they produce complementary false negatives. There are apparently a very large number of erroneous annotations in the databased mitogenome sequences, including missed genes, wrongly annotated locations, false complements, and inconsistent criteria for assigning the 5' and 3' boundaries; and I have listed many of these. The extent of overlap between genes is often greatly exaggerated due to inconsistent annotations, although notable overlaps involving tRNAs are apparently real. Finally, three novel hypotheses were examined and found to have support from the comparative analyses: (1) some organisms have mitogenomic locations that simultaneously code for multiple tRNAs; (2) some organisms have mitogenomic locations that simultaneously code for tRNAs and proteins (but not rRNAs); and (3) one group of nematodes has several genes that code for tRNAs lacking both the D and T arms.

Molecular Biology↗