Detrended correspondence analysis: A useful tool to quantify ecological changes from fossil data sets

Abstract

Fossil assemblages reflect the parental communities that produced them, and are in turn associated with specific environmental conditions. Thus, climatic and environmental changes are associated with changes in both the biotic communities and the fossil assemblages they produce. As a consequence, the environmental reconstruction of the past relies on the interpretation of multivariate fossil sequences that are commonly analyzed through dimensional rescaling techniques. Detrended correspondence analysis (DCA) has proven as an excellent technique to summarize ecological changes through time with the advantage of few prior assumptions and results that can be directly interpreted in terms of ecological turnover. In this paper we elaborate on a brief description of the technique and the interpretation of results, using a worked example on pollen and diatom data sets from Lago Verde (Los Tuxtlas, Mexico). With this worked example, we highlight the three basic ways in which DCA can provide useful approaches for a clear and relatively easy interpretation of the fossil data: i) identification of the ecological space through the a priori interpretation of species ordination; ii) localization of time slices within the ecological space defined by species, and quantification of the ecological turnover among samples; and iii) calculation of ecological distances as a means for putting individual samples into the historical context provided by the time frame in question.Keywords: Ecological distance, ecological turnover, ecological baseline, pollen, diatoms, detrended correspondence analysis (DCA). Resumen Los arreglos de fósiles coetáneos reflejan las comunidades parentales que los produjeron, las cuales están asociadas a su vez con condiciones ambientales particulares. Por lo tanto, los cambios climáticos y ambientales están inherentemente asociados con cambios en las comunidades bióticas y en los arreglos fósiles

Vegetation assemblages of central Mexico through the late Quaternary: modern analogs and compositional turnover

“…; Correa‐Metrio et al. ). Here we demonstrate it is also useful for studying resemblance among past and modern vegetation assemblages.…”

“…This technique summarizes the variability reflected in taxon composition, and ordinates both modern and fossil records within a common space with lower dimensionality (Correa‐Metrio et al. ). Rare taxa were down‐weighted within the DCA because they tend to influence dissimilarity metrics among samples and create spurious gradient length estimates (Eilertsen et al.…”

Multiphase response of palynomorphs to the Toarcian Oceanic Anoxic Event (Early Jurassic) in the Réka Valley section, Hungary

“…CA and DCA were used to assess similarities between the samples studied to explore relationships between the different marine palynomorph groups (Hill and Gauch, 1980;Kovach, 1993). Special emphasis was placed on the co-occurrences of the different marine palynomorph groups to help identify palaeoecological changes (Correa-Metrio et al, 2014). A taxon abundance matrix was used for the input of data.…”

“…Therefore the eigenvalues of the different axes cannot be interpreted as variance fractions (Hill and Gauch, 1980;Legendre and Legendre, 1998). The eigenvalues, by contrast, reflect the relative importances of the different axes (Legendre and Legendre, 1998;Correa-Metrio et al, 2014), and higher values account for more variance within the data. In this case Axis 1 is similar to the CA plot with an eigenvalue of 0.5842, compared to the significantly lower eigenvalue of 0.1638 for Axis 2 (Fig.…”

Responses to a warming trend and “El Niño” events in a tropical lake in western Mexico

“…Diatom data were handled with the TILIA program (Grimm 2004). A Detrended Correspondence Analysis (DCA) on the sediment (core and dredge) diatom data was done using the PAST program (Hammer et al 2001) to evaluate the changes in the diatom community through time (Correa Metrio et al 2014). …”