Forest Ecology and Management 435 (2019) 144–150 Contents lists available at ScienceDirect Forest Ecology and Management journal homepage: www.elsevier.com/locate/foreco Temporal changes in population genetics of six threatened Brazilian plant species in a fragmented landscape T ⁎ Miguel Busarello Lauterjunga, , Tiago Montagnaa, Alison Paulo Bernardia, Juliano Zago da Silvaa, Newton Clóvis Freitas da Costaa, Felipe Steinera, Adelar Mantovanib, Maurício Sedrez dos Reisa a Universidade Federal de Santa Catarina, Fitotecnia/Núcleo de Pesquisas em Florestas Tropicais, Florianopolis, Santa Catarina 55 48 3721 5322, Brazil b Universidade do Estado de Santa Catarina – Campus III Planalto Serrano, Engenharia Florestal, Lages, Santa Catarina, Brazil ARTICLE INFO ABSTRACT Keywords: Anthropic pressure has caused several changes in the environment, such as habitat loss and fragmentation. One Atlantic Rainforest effective way to evaluate its effects on population genetics is to monitor populations through time. We aimed to Natural regeneration characterize the population genetics of six plant species at two different times (cohorts). We asked (1) if po- Population monitoring pulations show genetic divergence between cohorts, (2) if any significant changes are present between the Apuleia leiocarpa genetic index of cohorts and, if so, (3) whether such changes are related to the adult cohort fixation index. To Dicksonia sellowiana address these questions, we studied 61 populations of 50 adult and 50 seedling individuals genotyped with Podocarpus lambertii allozyme markers. We calculated allelic richness (Ar), observed (Ho) and expected heterozygosity (He), and fixation index (f) for each population cohort; and pairwise FST between cohorts. Seedlings were genetically similar to the adults (mean pairwise FST = 0.014). No difference was found in the proportion of populations that showed increases and decreases of the genetic indexes over cohorts, except f, for which more populations − showed a decrease. Adult fixation index had a correlation with Ho (r = 0.507, p = 3∙10 5) and He (r = −0.247, p = 0.055). A mean test between cohorts revealed the maintenance of high f values in Araucaria angustifolia and Ocotea catharinensis, as well as a significant decrease in He of Euterpe edulis, species widely explored in the past. Although we only studied two cohorts, general trends and significant changes were detected, which could be important in the conservation of those six species. 1. Introduction Moreover, longevous species, such as trees, often present resilience after disturbance events (i.e., time lag) when analyzing genetics, no Destructive anthropic pressures are negatively affecting all levels of consensus has been reached on how they are affected by external biodiversity, subsequently changing the environment within just a few pressures (Young et al., 1996; Kramer et al., 2008; Lowe et al., 2015). decades (Millennium Ecosystem Assessment, 2005). The main human- One way to minimize the effects of time lag is to work with seedlings related threats to biodiversity are fragmentation and habitat loss (e.g., Carvalho et al., 2015; Montagna et al., 2018a), or monitor po- (Primack, 2004), with the later leading to direct reduction in biodi- pulations over time, i.e., cohorts. Monitoring of populations genetics is versity (Fahrig, 2003). Genetic diversity (i.e., intraspecific variation) is recommended for conservation purposes (Mimura et al., 2017), but one of the affected levels of biodiversity associated with long-term relatively few studies have monitored the population genetics of’ trees conservation (Primack, 2004), and its loss can have consequences si- (e.g., Wojnicka-Półtorak et al., 2013, 2017; Catherall et al., 2018) and milar in magnitude to those at demographic levels (Frankham, 2003). then only rarely with more than one study site (e.g., Westergren et al., However, population genetics has received less emphasis when com- 2015) or species (e.g., Kettle et al., 2007). For those reasons, monitoring pared to other disciplines when it comes to conservation issues (Laikre, studies with multiple populations and species across the same land- 2010). scape and affected by similar pressures can reveal patterns about how The impacts on genetics vary according to each landscape context the population genetics of each species is affected by landscape changes and the studied species (Young et al., 1996; Lowe et al., 2015) since over the years, which can, in turn, inform conservation policies and different ecological traits can influence the genetics of a species management. (Hamrick and Godt, 1996; Broadhurst et al., 2017; Lowe et al., 2018). One biome highly altered in the last century is the Atlantic ⁎ Corresponding author. E-mail address: [email protected] (M.B. Lauterjung). https://doi.org/10.1016/j.foreco.2018.12.058 Received 25 October 2018; Received in revised form 28 December 2018; Accepted 30 December 2018 0378-1127/ © 2019 Elsevier B.V. All rights reserved. M.B. Lauterjung et al. Forest Ecology and Management 435 (2019) 144–150 Rainforest, a biodiversity hotspot (Myers et al., 2000; Mittermeier et al., (MMA) 2014; IUCN, 2017). 2011) which has suffered a huge area reduction, now with only 11.7% We used at least 10 allozyme loci for genetic characterization of of its original area left (Ribeiro et al., 2009). Because of such reduction, each species (Table 2), following the procedures described by Alfenas many species have, correspondingly, suffered a reduction in the number (1998). Allozymes were used because of their simplicity and their costs, of individuals and habitats, criteria used to classify species as en- which made a study of this extent possible (61 populations of 100 in- dangered (IUCN Standards and Petitions Subcommittee, 2014). Santa dividuals, divided over six different species). Moreover, they were Catarina is a Brazilian state which holds one of the biggest proportions adequate for our study questions (see Freville et al., 2001, Sun et al., of remaining Atlantic Rainforest, and it is well characterized for its 2001, Conte et al., 2008). For other studies, such as fine-scale spatial biodiversity (Vibrans et al., 2012c), including the genetics of some tree genetic structure, paternity analysis or reproductive system studies, species (Reis et al., 2012; Montagna et al., 2018c). However, most of markers with higher exclusion power should be used, such as SSR. the remaining fragments are smaller than 50 ha (Vibrans et al., 2012a), ff and the current state of the landscape has direct e ects on vegetation 2.2. Data analysis descriptors (Schaadt and Vibrans, 2015), which could also be expected for genetics descriptors. We used the following genetic indexes to characterize the two co- Therefore, this study aimed to characterize the population genetics horts from each population: allelic richness (rarefied, Ar), effective of six endangered plant species at two distinct moments in time (two number of alleles (Ae), observed (Ho) and expected heterozygosity (He; cohorts) in a fragmented landscape and to verify possible temporal genetic diversity index, Nei, 1973), and fixation index (f, (He-Ho)/He). changes in their population genetics. We asked (1) if populations show We constructed 95% confidence intervals (CI) via 10,000 bootstraps for fi genetic divergence between cohorts, (2) if any signi cant changes are each index except Ar, since it was rarefied. Allelic richness and ex- present between the genetic index of adult and seedling cohorts and, if pected heterozygosity are, respectively, measures of richness and di- fi so, (3) whether such changes are related to the adult cohort xation versity in the genetic level, and fixation index indicates the potential of index. genetic diversity loss between generations. To verify if populations showed genetic divergence between cohorts 2. Methods (Question 1), we calculated the pairwise FST values (Weir and Cockerham, 1984) between adults and their respective seedlings co- 2.1. Data collection hort. Significance was obtained through 10,000 bootstraps CI. The FST values range from 0 to 1, indicating genetic similarity (FST =0) to Our study area covered the entirety of Santa Catarina state, which complete divergence (FST = 1). presents a fragmented landscape of the Atlantic Rainforest biome To determine the existence of any significant changes between the (Fig. 1). Data collection was carried out from 2003 to 2015 as part of genetic indexes of adults and seedlings (Question 2), we performed the Floristic and Forest Inventory of Santa Catarina Project (IFFSC, pairwise comparisons between them, using 95% CI mentioned above, Vibrans et al., 2010; Reis et al., 2012). The project sampled 61 popu- and verified if genetic indexes increased or decreased between cohorts, lations, each consisting of two cohorts: adults, the oldest/largest in- subtracting the genetic index values of the adults from the seedlings (S - dividuals in the stand, generally presenting reproductive structure, and A). Positive values show an increase (S > A) of the index over cohorts, seedlings, the smallest individuals, with heights < 1 m. We collected at and negative values show a decrease (A > S). We then performed a least 50 individuals per cohort, spaced 50 m apart to reduce the chance Chi-squared test to see if this proportion was random, and a Pearson of sampling related individuals. correlation test between changes in genetic indexes (S - A) and adults The studied species were Apuleia leiocarpa (n = 5 populations), fixation index (Question 3). Because