\draw[step=1cm, help lines] (-2,-2) grid (2,2);
\foreach \x in {1,...,5} \draw (\x-3,-2 + .1)--(\x-3,-2 -.3) node[below] {\footnotesize $\x$};
\foreach \y in {1,...,5} \draw (-2 + .1, \y-3)--(-2 -.3,\y-3) node[below] {\footnotesize $\y$};
% \draw[fill=gray, draw=gray] (0,0) circle [radius=0.225cm];
% \draw[fill=blueind, draw=blueind] (1,0) circle [radius=0.225cm];
% \draw[fill=blueind, draw=blueind] (0,1) circle [radius=0.225cm];
% \draw[fill=red, draw=red] (-1,0) circle [radius=0.225cm];
% \draw[fill=red, draw=red] (0,-1) circle [radius=0.225cm];

% % Légende
% \node[font=\tiny, text justified,fill=none, rotate=-45] (Splits) at (0.5,0.5){{\color{blueind} Splits}};
% \node[font=\tiny, text justified,fill=none, rotate=-45] (Merges) at (-0.5,-0.5){{\color{red} Merges}};

% % Splitting
% \draw[>=stealth,->,thick, draw=blueind] (0.225,0) -- +(0.55,0);
% \draw[>=stealth,->,thick, draw=blueind] (0,0.225) -- +(0,0.55);

% % Merging
% \draw[>=stealth,->,thick, draw=red] (-0.225,0) -- +(-0.55,0);
% \draw[>=stealth,->,thick, draw=red] (0,-0.225) -- +(0,-0.55);

% Axes
\draw[>=to,->,thick] (-2,-2) -- +(4.3,0);
\node[font=\small, fill=none] (Q_1) at (2.6,-2) {$Q_1$};
\draw[>=to,->,thick] (-2,-2) -- +(0,4.3);
\node[font=\small, fill=none] (Q_2) at (-2, 2.6) {$Q_2$};

% Init
\onslide<1->{
    \draw[fill=gray, draw=gray] (-1,-2) circle [radius=0.225cm];
    \draw[fill=gray, draw=gray] (-2,-1) circle [radius=0.225cm];
    \draw[fill=gray, draw=gray] (-2,-2) circle [radius=0.225cm];
}
\onslide<2->{
    % New models
    \draw[fill=blueind, draw=blueind] (0,-2) circle [radius=0.225cm];
    \draw[fill=blueind, draw=blueind] (-2, 0) circle [radius=0.225cm];
}
\onslide<2-3>{
    \draw[fill=blueind, draw=green, very thick] (-1,-1) circle [radius=0.225cm];
}
\onslide<2>{
    % Splits
    \draw[>=stealth,->,thick, draw=blueind] (-1 + 0.225,-2 + 0) -- +(0.55,0);
    \draw[>=stealth,->,thick, draw=blueind] (-1 + 0, -2 + 0.225) -- +(0,0.55);

    \draw[>=stealth,->,thick, draw=blueind] (-2 + 0.225,-1 + 0) -- +(0.55,0);
    \draw[>=stealth,->,thick, draw=blueind] (-2 + 0, -1 + 0.225) -- +(0,0.55);
}

\onslide<3>{
    % updated models
    \draw[fill=blueind, draw=blueind] (-1,-1) circle [radius=0.225cm];
    \draw[fill=red, draw=red] (-2, -1) circle [radius=0.225cm];

    % merge
    \draw[>=stealth,->,thick, draw=red] (-1 - 0, -1 - 0.225) -- +(0,-0.55);
    \draw[>=stealth,->,thick, draw=red] (-1 - 0.225, -1 - 0) -- +(-0.55,0);

    %splits
    \draw[>=stealth,->,thick, draw=blueind] (-1 + 0.225,-1 + 0) -- +(0.55,0);
    \draw[>=stealth,->,thick, draw=blueind] (-1 + 0, -1 + 0.225) -- +(0,0.55);
}

\onslide<3->{
    \draw[fill=blueind, draw=green, very thick] (-1,0) circle [radius=0.225cm];
    \draw[fill=blueind, draw=blueind] (0,-1) circle [radius=0.225cm];
}