Research experience exclusively in Zoology and Evolution.  I am mainly devoted to study the ecological an evolutionary patterns of morphological diversification in insects, exploring the way in which morphological variation occurs, which is the evolutionary origin.  For this purpose, I use geometric morphometric tools and morphological analyses in multiple levels.  Currently, as part of my PhD, I am studying the combination of these methods with experimental protocols of quantitative genetics, morphological integration and modularity as well as the combination of macroevolutionary questions with a comparative approach in a phylogenetic context.

 

My research fields are:

 

Geometric Morphometrics model

Most of my research efforts in geometric morphometrics have concentrated on landmark data (Benitez et al 2010;2011a,b;2012). Morphological landmarks are points that can be located precisely on each specimen under study with a clear correspondence in a one to one manner from specimen to specimen (Klingenberg 2008a, Zelditch et al 2012).

 

 

The principal and most important analysis of geometric morphometrics is called Procrustes superimposition, where only the shape information is extracted and the other components of variation in size, position and orientation can be removed, while taking care not to alter shape in any step of the procedure (Figure left Benitez, data not published, Figure right Benitez et al 2011b) (Rohlf & Slice 1990, Goodall 1991, Dryden & Mardia 1998). The extra components of variation can be removed by rescaling the configurations to a standard size, shifting them to a standard position, and rotating them to a standard orientation. Moreover, since none of the steps has changed the shape of the configurations, the variation after the procedure is the complete shape variation.

 


 

Morphological Integration and Modularity

Understanding integration and modularity is essential to comprehend the evolution of shape since the coherence of recognizable parts of most organisms is dependent on their developmental origin, structure and function (Klingenberg 2008, Klingenberg 2010).Integration is the cohesion among traits that results from interactions of the biological processes producing the phenotypic structures under study.

 

 

 

 

 In a morphometric study, the relevance of studying integration is due to the fact that it directly affects the evolutionary directionality by means of correlated effects of mutation on phenotypic variation; and modularity affects the capacity of complex systems to evolve limiting the mutational effect to a set of related characteristics, both functional and developmental (Raff, 1996; Raff & Sly, 2000; Wagner &Mezey, 2004; Wagner et al., 2007; Mitteroecker&Bookstein, 2007), and therefore it would also affect the potential deleterious effects of these mutations in fitness.

Morphological integration and modularity, as well as channeling, novelties and constraints, represent fundamental paths where development would have the main role to explain evolution (evo-devo).

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Development Stability Measurement: Fluctuating Asymetry

 

Development stability (DS) is defined as the capacity of an organism to produce a phenotype predetermined by an adaptative body design under a set of specific genetic and environmental conditions (Waddington, 1942). This is, therefore, referred to the intrinsic capacity of an individual to overcome accidents and disturbances during growth and development (Clarke, 1998).

The measuring tool that is most commonly used to estimate DS is Fluctuating Asymmetry (FA) (Van Valen, 1962; Palmer & Strobeck, 1986; Palmer, 1994; Clarke, 1998; Pither & Taylor, 2000).  FA is a measure of small random deviations occurring between left and righ side of bilaterally symmetrical traits (Van Valen, 1962).  The main idea in using FA as an development stability measurement is that left and right sides (L - R) of an organism may be seen as independent replications of the same development, where body sides of an individual would share the same genotype in an homogeneous environment (Benitez & Parra 2012). In other words, the factors determining development of L and R sides would be identical, and therefore in ideal conditions they would be expected to be perfectly symmetrical (Auffray et al 1999; Klingenberg, 2003; Van Dongen, 2006, Benitez et al 2008). 
 

 

 

Fluctuating asymmetry (FA) is particularly interesting as a result of its potential as a biomonitor of environmental quality in the last 5 years I have devoted my interest in analyse the efect of developmental stability principally how is reflected on the morphology. A review of this area in Spanish you can read in Benitez & Parra 2012 principally from the classical fluctuating asymmetry.

 

 

Ecology + Shape Analysis 



One of the great characteristics of GM is that it allows studying the association between shape and other kinds of data, such as ecological, genetic, biomechanical, or other relevant factors. This is really useful because one of the traditional interests of ecologists is to associate character states or different phenotypic values with environmental data (Benitez et al 2014). For instance, ecomorphological studies have revealed constraints and selective factors affecting the phenotypic response to certain environments, how morphology influences the ecological distribution of a particular phenotype and evolutionary trends such as phylogenetically conserved morphologies. In all these cases, morphology represents certain organismal aspects that relate and individual to its environment, hence its importance. Indeed, the association between morphology and ecology could provide useful insights about the expression of the phenotype-environment interaction and the related evolutionary history.
 

 

 

Pest Ecology and Shape Analysis

 A big collaboration with the Faculty of Agriculture, Department for Agricultural Zoology at University of Zagreb (Croatia) with the Colleagues Dr Renata Bažokand Darija Lemic, has emphasised the study of the shape adaptation on the Western corn rootworm (WCR) (Diabrotica virgifera virgifera LeConte). This pest is an invasive species accidentally introduced from North America into Europe. WCR is potentially the most serious pest of maize production (Lemic et al 2014). The WCR overwinters in the soil only to emerge in spring and commence feeding upon the roots of maize plants damaging key plant physiological processes. In this area lot of works studying the adaptive pattern of wing and body shape correlated to the invasiveness are in process with some articles already published studying the asymmetry, and integration patterns of the wing (Benitez et al 2014 (BJLS), Lemic et al 2014 (ZA), Benitez et al 2014b (ZA)).


 

 

Sexual Dimorphism and Shape Evolution

Sexual dimorphism is one of the most notable and generalized sources of phenotipic variation in animals and plants and therefore it have raised much interest in evolutionary biology (Fairbairn & Preziosi 1996).  Generally, dimorphism is attributed to sexual selection, a process related to selection based on success of differential mating and which may also generate fast adaptive responses in organisms (Fairbairn & Preziosi 1996, Benitez et al 2010a).  However, theoretical as well as empirical studies have determined that sexual dimorphism reflects the net effect from both natural and sexual selection, which could be acting under different types of constraints whether genetic, phylogenetic or ontogenetic, limiting the response to this selection. (Slatkin 1984; Arak 1988; Hedrick & Temeles 1989; Shine 1989, 1991; Fairbairn 1990; Arnqvist 1994).

 

Shape studies in Ceroglossus chilensis have argued that sexual dimorphism is generally concentrated in two sections of body shape:  in the abdominal section, where these dimorphism variations are associated with an adaptative character due to the presence of eggs in females, and changes in the pronotal section associated to male-male competence due to variations of sex ratio in populations, (Benítez et al., 2010a; 2010b). 

 

Other studies have used the geometric variation of wing shape in insects as a dimorphism character, where the integrated geometric variation of veins is differentiated between males and females (Benítez et al., 2011). 


 

Shape variation and Isolated Population

The alteration of habitat generates different degrees of stress in insects, which are a product of the different types of alterations that affect their ontogeny, and whose affects may produce asymmetric phenotypes. (Benitez et al 2011b)

Since the last century, research on islands has continued to advance the understanding of the evolutionary process. Islands archipelagoes provide unique scenarios for studying the roles of geography and ecology in driving population divergence and speciation, moreover played a crucial role in the diversification of biotas, and oceanic islands have long been recognized as natural laboratories for the study of evolutionary processes (Mayr 1967, Grant 1998, Lossos & Ricklefs 2009, Mila et al 2010).

. Due to the isolation that affect our populations, the gene flow has been interrupted between them and the group shows a particularly high plasticity in the capacity to withstand differences and environmental pressures imposed in each particular environment. This capacity has been reflected in the high morphological plasticity emerged and indicates that the populations are evolving. (Benitez et al 2012a in reviewers)