Beyond overpopulation: a comment on Zawistowski et al. and Salman et al

The intentional production and destruction each year of millions of companion animals is a sobering fact. The need for meaningful statistical data on this phenomenon is urgent. No less pressing, however, is the need for a conceptual framework to make sense of the empirical findings. The conventional focus on overpopulation is inadequate and places unnecessary limits on the way in which the problem is approached. I propose in its place a market-based model that takes seriously the role of consumer demand and considers the flaws and inefficiencies distorting the market for companion animals. Shifting attention to the choices consumers make in acquiring and discarding animal companions suggests new possibilities for change and provides a useful focal point for further empirical work.     

Technical comment on Adler et al. (2006): experimental design compromises conclusions

The conclusion that herbivory induces 'alkaloids' in nectar but not in leaves, is likely an artefact of using pot-bound plants and analytical procedures that only measure anabasine, a minor alkaloid representing 0.3% of the total alkaloids produced by Nicotiana tabacum.     

Caveats on the use of fossil calibrations for molecular dating: a comment on Near et al

We reassess a study on a fossil-calibrated molecular clock that provides a new method for evaluating the accuracy of calibration points. We address several pitfalls that molecular systematists should be aware of when calculating rates of molecular evolution based on fossil calibrations. These caveats involve the substantiation and accurate use of geologic dates, the inappropriate use of fixed calibration points, and the explicit and objective phylogenetic placement of fossil taxa. Paleontological data, like molecular data, should be treated with the utmost rigor.     

Deviation from the line of least resistance does not exclude genetic constraints: a comment on Berner et al. (2010)

Berner et al. (2010) found that freshwater adaptation of three-spined sticklebacks had not followed the direction of maximal evolvability. Based on this, they suggested that ancestral variance structure has not appreciably biased adaptive diversification. We reanalyze their data to show that evolution has happened in directions of much larger than average evolvability, and we conclude that their data are consistent with an influence of ancestral variational constraints.     

Technical comment on Condamine et al. (2019): a cautionary note for users of linear diversification dependencies

Condamine et al. (2019; 22: 1900–1912) fitted linear and exponential functions of time‐dependent, diversity‐dependent and temperature‐dependent diversification to investigate diversification dynamics of tetrapod families. Here I highlight potential misinterpretations when using linear diversification dependencies and provide some clarifications.     

Grooming and social cohesion in primates: a comment on Grueter et al.

Grueter et al. have recently claimed that grooming time in primates is best explained by terrestriality, which they take to be a proxy for hygiene demand. We suggest that their results arise from a confound between terrestriality and other aspects of sociality, combined with a number of conceptual and sampling problems.     

Benthic habitats do show a significant latitudinal diversity gradient: A comment on Kinlock et al. (2018)

The latitudinal diversity gradient (LDG) has been investigated for decades, with hundreds of studies focusing on different organisms, regions and habitat types. Meta‐analysis may be considered, therefore, a useful tool to explore the generality and limitations of this remarkable macroecological pattern. The first meta‐analysis exploring variations in the LDG, published by Hillebrand in 2004, revealed that the latitudinal decline in species richness seems to be indeed a general phenomenon. However, Kinlock et al. (2018, Global Ecology and Biogeography, 27, 125–141) revisited recently the challenge of synthesizing individual LDGs and indicated that the phenomenon is not ubiquitous among habitats of the marine realm. More precisely, they indicated that the phenomenon is non‐significant in the benthic habitat. Here, we suggest that the marine habitat categories used by them (i.e., benthic, coral reefs, coastal, open ocean) are not independent and that reclassifying the studies significantly alters one of their main results. By assigning the studies into benthic and pelagic categories, and additionally into coastal or oceanic zones, we show that non‐ambiguous, evolutionarily meaningful marine habitats display a significant latitudinal decline in species richness.     

Persistence and recolonisation determine success of bog restoration for aquatic invertebrates: a comment on Mazerolle et al. (2006)

1. Mazerolle et al. (2006) concluded that some aquatic invertebrate species, including bog‐associated species, readily colonise man‐made bog pools. In contrast, in Dutch bog remnants Van Duinen et al. (2003) found that a considerable number of bog‐associated species do not colonise newly created bog pools. 2. The conclusion of Mazerolle et al. (2006) is based on vagile aquatic invertebrates. Here, we question whether their conclusion can be extended to more sedentary species, which were not captured in the Canadian study, but made up an important part of the invertebrate assemblage in the Dutch study. This discrepancy could be caused by sampling artefacts, low colonisation rates of these species or an incomplete restoration of site conditions. 3. In Canada, chances of recolonisation may be higher than in the Netherlands, as natural and near‐natural bogs are more extensive. In the Netherlands, with low chances of recolonisation, persistence of species may be more important. To disentangle the relative importance of persistence and recolonisation, evaluations of the success of restoration projects need to cover the entire invertebrate assemblage, including both vagile and more sedentary species.