Morphoscape Ecology: assessing the variability of beetle forms across habitats
Most of the metrics to assess anthropogenic impacts used, and still use, features of living communities, such as species richness. More recently, however, ecologists also began focusing on species quality by measuring the diversity of evolutionary lineages within habitats and regions, as well as functional traits of particular ecological importance (e.g., body mass, type of locomotion, specializations of the feeding apparatus etc.). These metrics are commonly used by governmental agencies in different countries when monitoring the quality of the environment and are at the basis of political decisions for environmental regulators.
In our study, we focused on a widespread and diverse family of beetles, the Carabidae, and measured how big their morphoscape is across four types of habitats (cropland, meadow, poplar stand, and woodland) found in the Padana Plain of northern Italy. Using museum specimens, and available information on species composition, we selected a single adult male individual for each species found in the four habitats and applied a method of image analysis to quantify body size and body shape using digital photos. Within a habitat, the magnitude of the morphoscape was quantified using different metrics. The most intuitive of these is simply the range of variation, which is analogous to computing the difference between the tallest and shortest person in a group of people to estimate how much individuals differ in that sample.
We discovered that body size partly mirrored differences in species richness, with more variation in the habitat with more species, regardless of human impact. Thus, open habitats, such as meadow and cropland, housed a wide range of body sizes, as well as more species of carabid beetles (respectively ca. 100-110), despite being under stronger anthropogenic pressures. However, woodland, the least impacted habitat, had about as much size variation across species as cropland and meadow, and consistently showed the biggest morphoscape for shape. This is particularly remarkable if one considers that cropland, in fact, had a morphoscape almost as big as woodland, but woodland reached that magnitude despite being host to almost 20% fewer species than cropland. This suggests that even if a relatively pristine closed woodland habitat could be less species-rich, it might, in fact, conceal a relatively higher number of morphologies and be thus potentially richer in the ecological functions played by its fewer but more disparate members.
Using an analogy, it is like having two companies, that we call C and W, renting vehicles for different types of work: both companies have a full range of sizes going from small bikes to big trucks; C has more brands; however, W can offer some less common types of vehicles, for instance, auto-rickshaws and caravans, that are not available at C.
Citation:
Fontaneto, D., Panisi, M., Mandrioli, M. et al. Estimating the magnitude of morphoscapes: how to measure the morphological component of biodiversity in relation to habitats using geometric morphometrics. Sci. Nat. (2017) 104: 55. https://doi.org/10.1007/s00114-017-1475-3
[Ultimo aggiornamento: 12/06/2018 14:59:51]